SPACE NEWS

SPACE NEWS 07
of Extra-Solar Space
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. . Note, too, that there's 8 times more H floating free than there is in stars.
. . This is the clearest explanation I've found on dark energy & the expansion of the universe (eXit to return).

* My (prob'ly wacky) idea: the so-called anti-gravity now known to exist between galaxies --pushing them apart & speeding up the expansion-- must also push IN on the edges of all widely-separated galaxies. This would make them more compact & would rotate faster, making it seem like they're heavier than they are. i.e. they don't rotate fast because there's a heavy center --BH or not, but because it's Anti-Grav "pushing", rather than gravity "pulling". I wonder if this has been inserted into their calculations.

Neutron star gravity: 300,000 times that at Earth.

If the sun collapsed into a singularity, its event horizon would measure approximately 3 km across. If Earth followed suit, its event horizon would only measure 1 centimeter.

For perhaps its first million years, the Universe was small and dense enough that sound waves could travel through it [!] --so efficiently, in fact, that they moved at about half the speed of light! 500,000 X as fast. & the Universe was so small then, sound cuda gotten across quickly.

The Milky Way in its entirety spans more than 100,000 light-years.

Feb 2003: a joint NASA–Princeton University satellite, the Wilkinson Microwave Anisotropic Probe, produced a high-resolution map that captured the oldest light in the universe. This ancient light, called the cosmic microwave background, is the cooled remnant of the Big Bang. This has accurately determined the age of the universe -—with just a 1% margin of error: 13.7 billion years old.
. . The Earth is 4.6 billion years old.

NEWS:

Dec 28, 07: Astronomers have observed for the first time a jet of matter spiraling outward from an infant star, as if a lengthy strand of curly pasta. The enormous jet, which shoots out in two directions, is rocketing material away from the so-called protostar and into interstellar space at more than "supersonic speeds." From end to end, the bipolar jet extends 16,000 AU. "Ultimately this object we observed will grow into a star like [Sol], but right now it's only 6% of the mass."
. . There's a stellar glitch of sorts. Similar to dizzying rides that rotate so swiftly riders stick to the outer walls, as a disk rotates faster and faster, the swirling matter sticks to the disk's outer edge. The gas can't fall inward toward the star until it sheds excess spin power called angular momentum. Theory suggests nascent stars could shed excess angular momentum in the form of gas spiraling outward around shooting jets.
. . Measurements showed matter rotating around the jet's axis in a sort of "reverse whirlpool." The results suggest the bipolar jet moves outward at a speed greater than 322,000 kph.

Dec 20, 07: Dust littered the early universe and seeded the formation of rocky planets such as the Earth. But where, exactly, most of the celestial grit came from was uncertain until now.
. . Astronomers have found 10,000 Earth masses worth of dust surrounding Cassiopeia A, the remnants of a supernova about 11,000 light-years away from our planet. The NASA Spitzer Space Telescope observations show silicates, carbon, iron oxide, aluminum oxide and other dust-forming chemicals around the blown-out star. Jeonghee Rho, an astronomer at the Caltech in Pasadena, Calif., thinks the discovery signals the first strong evidence that massive exploding stars really are the litterbugs of the universe.
. . Stars like Sol are thought to burn too long to seed the cosmos with enough grit, and massive stars are probably too gassy and short-lived, the thinking goes. Cassiopeia A's explosion is extremely recent —-the light reached Earth just 325 years ago-— but Rho and her team think cosmic dust balls similar to the remnant began producing the stuff of terrestrial planets billions of years ago. Within Cassiopeia A, the astronomers found cool yet freshly-made dust mixed in with jettisons of gas called "unshocked ejecta" deep inside the supernova leftovers.
. . Set to launch in 2008, scientists hope to use the European Space Agency's Herschel spacecraft to find such cold dust near quasars, thought to be hyperactive black holes, which X-ray observations suggest could produce the stuff.

Dec 18, 07: A cosmic explosion that seems to have come out of nowhere -—thousands of light-years from the nearest collection of stars—- has left astronomers baffled. The blast, one of the brightest this year, was detected by spacecraft from the Inter-Planetary Network on Jan. 25, 07 and satellites were used to pinpoint its location to a region of the sky in the constellation Gemini.
. . The explosion was a type called a long-duration gamma-ray burst (GRB), which are thought to be powered by the death of a massive star. But images taken after the glow of the burst, dubbed GRB 070125, had faded away showed no galaxy at the location.

Dec 18, 07: Antimatter is awesome, primarily because when it touches its oppositely charged counterpart —-matter-— both are annihilated in a burst of gamma radiation. But stabilize the matter-antimatter mix into a substance called positronium —-as a couple of UC Riverside physicists did for a record-breaking 100 nanoseconds-— and you're on your way to turning that jolt into a focused, ultrapowerful laser. Oh, and the researchers might also learn why there's so little antimatter in the universe.

Dec 17, 07: A "death star" galaxy is sending out a powerful jet of particles and magnetic radiation that is likely obliterating any possible life in its broad path, notably in a nearby galaxy, astronomers said. They said the two galaxies appear to be merging and the disturbance in the magnetic field caused by this movement may have awakened a dormant, supermassive black hole in one of the galaxies.
. . The two galaxies appear to be in the process of a billion-year-long-merger. "They are actually doing somewhat of a dance around each other. Both galaxies have supermassive black holes at their centers, and 3C321, the larger galaxy, is emitting this stream of energy and particles. The unnamed smaller galaxy apparently has swung into the path of this jet. The magnetic field of any planet would be compressed, leaving it vulnerable to solar storms from its star.
. . The astronomers agree that both galaxies are likely to have planetary systems but nothing resembling life on any planet could survive the blast. While such jets have been seen before, this is the first time one has been observed battering another galaxy.
. . "There are tens to hundreds of millions of stars in the path. Some of those stars almost certainly have planets", said Martin Hardcastle, an astrophysicist. There is no need to worry about this death ray hitting Earth --the galaxies are 1.4 billion light years away.

Dec 12, 07: Milky Way Galaxy has two distinct parts in its outer reaches that rotate in opposite directions, astronomers announced.
. . The galaxy has a bulbous core where stars are tightly packed and orbiting rather furiously around the central black hole. Then there's the big flat disk with its spiral arms, also orbiting the galactic center somewhat in the manner of a hurricane's spiral bands. We live on one of those arms. Around it all is a halo of stars that don't all behave in such an orderly fashion. Now they find the halo has two parts.
. . "By examining the motions and chemical makeup of the stars, we can see that the inner and outer halos are quite different beasts and they probably formed in different ways at different times."
. . The main galactic disk, home to our sun, rotates counterclockwise as seen from above at an average speed of 500,000 mph. Surrounding the disk is what's now called the inner halo. It orbits in the same direction at about 50,000 mph. The outer halo, a sparsely populated region, spins in the opposite direction at roughly 100,000 mph. [say WHAT?! . Seems impossible! I bet they got that backwards.]
. . There are chemical differences between the two parts, too. Stars in the inner halo have three times as many heavy atoms, including iron and calcium. These heavy elements were produced by massive stars that exploded fantastically and begat subsequent generations of stars.
. . The study adds to other evidence showing the galaxy was not built in a cosmic day. Rather, it assembled over time, gobbling smaller galaxies in one of nature's greatest construction projects.
. . The inner halo probably formed first, from collisions between smaller galaxies that had been captured by the Milky Way's gravitation. The outer halo formed later, the thinking goes, as small galaxies (orbiting opposite our own) were lured in and torn apart.

Dec 11, 07: Traces of a distant extrasolar planet's hazy red sunset have been detected for the first time. Astronomers pointed the Hubble Space Telescope HD 189733b, a gaseous Jupiter-like world about 63 light-years from Earth, as it passed in front of its parent star to catch a glimpse of the planet's atmosphere. Previous observations have not revealed much about the planet's atmosphere, other than that it has clouds.
. . They expected to see the fingerprints of sodium, potassium and water in the red haze, but instead discovered iron, silicate and aluminum oxide (which sapphire gems are made of). The composition is similar to Venus and Saturn's moon Titan -—both worlds with very thick air.
. . So far, HD 189733b isn't thought to harbor any Earth-sized moons or Saturn-like rings, but more powerful telescopes of the future might detect them.

Dec 10, 07: Cosmologists are always complaining about their inability to find the dark matter in the universe, invisible stuff that's supposedly more prevalent than regular matter. They don't even know what it is, so of course they can't see it.
. . Meantime, a whole bunch of normal matter is missing, too. A new computer model at least suggests where some of that missing normal matter might be. Regular matter makes up only about 5% of the universe.
. . While scientists have no clue when they'll actually find dark matter, they'd really like to square the cosmic ledger a bit by tallying up all the regular matter that theory holds should exist. Only about 40% of it is in the books yet. The rest, according to the new simulation, is gas that's caught in a tangled web of cosmic filaments that are hundreds of millions of light-years long. The filaments connect clusters of galaxies, and the gas within the filaments is hidden by huge gas clouds.
. . This conclusion is based on a new computer model that took nearly 10 years to make. It models a region of space equal to 2.5% of the visible universe and showed how matter collapsed due to gravity and became dense enough to form the cosmic filaments, galaxy structures and the clouds that hide the filaments.

Dec 6, 07: For years, scientists have wrestled with a puzzling fact: The universe appears to be remarkably suited for life. Its physical properties are finely tuned to permit our existence. Stars, planets and the kind of sticky chemistry that produces fish, ferns and folks wouldn't be possible if some of the cosmic constants were only slightly different.
. . Well, there's another property of the universe that's equally noteworthy: It's set up in a way that keeps everyone isolated. We learned this relatively recently. The big discovery took place in 1838, when Friedrich Bessel beat out his telescope-wielding buddies to first measure the distance to a star other than the sun. 61 Cygni, a binary star in our own back yard, turned out to be about 11 light-years away.
. . Traveling between the stars is a tough assignment. To hop from one to the next at the speed of our snazziest chemical rockets takes close to 100,000 years. For any aliens who have managed to amass the enormous energy reserves and ponderous radiation shielding required for relativistic spaceflight, the travel time is still measured in years
. . This has some obvious consequences (which, remarkably, have escaped the attention of most Hollywood writers.) To begin with, forget about galactic "empires" or more politically-correct "federations." Two thousand years ago, the Romans clubbed together an empire that stretched from Spain to Iraq, with a radius of about 1,200 miles. They could do this thanks to organization and civil engineering. All those roads (not to mention the Mediterranean) allowed them to move troops around at a few miles an hour. Even the most distant Roman realms could be reached in months or less,
. . In the 19th century, steamships and railroads increased the troop travel speeds by a factor of ten, which extended the radius of control by a similar amount. The British could rule an empire that was world-wide.
. . But here's the kicker: Even if we could move people around at nearly the speed of light, this "1% rule" would still limit our ability to effectively intervene –-our radius of control-– to distances of less than a light-year, considerably short of the span to even the nearest star other than Sol. Consequently, the Galactic Federation is a fiction (as if you didn't know). Despite being warned that Cardassian look-alikes were wreaking havoc and destruction in the galaxy's Perseus Arm, you couldn't react quickly enough to affect the outcome. And your conscripts would be worm feed long before they arrived on the front lines anyway. In other words, aliens won't be getting in one another's face.
. . There's a similar argument to be made for communication. We seldom initiate information interchange that takes longer than months (an overseas letter, for instance). More generally, we seldom begin any well-defined project that lasts more than two or three generations. The builders of medieval cathedrals were willing to spend that kind of time to complete their gothic edifices, and those who bury time capsules are occasionally willing to let a hundred years pass before the canisters are dug up. But what about a project that takes several centuries, and possibly millennia? Who's willing to do that? Only Stewart Brand's "Long Now Foundation" seems to have the guts for this type of enterprise, proposing to build a clock that will keep time for ten thousand years.
. . Clearly, these simple observations must have implications for SETI which, as we noted, involves transmissions that will be underway for hundreds to thousands of years. In particular, if there are signals being bandied about the galaxy for purposes of getting in touch, either (1) the aliens are individually much longer-lived than we are, which – if you're a fan of circuit-board sentience – implies that they're probably not biological. Or (2) we're missing some important physics permitting faster-than-light communication, and extraterrestrial signaling efforts don't include burping light and radio waves into space.
. . So while the cosmos could easily be rife with intelligent life –-the architecture of the universe, and not some Starfleet Prime Directive, has ensured precious little interference of one culture with another.
. . SethShostak, Senior Astronomer, SETI

Dec 3, 07: The first stars to form in the universe may not have shone like those today, but instead may have been invisible "dark stars" powered by the annihilation of dark matter, a new study finds. And, researchers say, they would have been gargantuan.
. . Dark matter, invisible stuff which scientists think makes up the bulk of the universe, has been considered to have role in the evolution of the early universe but not in the formation of the first stars.
. . For the new study, astrophysicists calculated how dark matter would have affected the temperature and density of the gas that clumped together to form the first stars. The findings suggest that dark matter particles interacted so that they "annihilated" each other, producing subatomic particles called quarks and their antimatter counterparts, antiquarks. This annihilation produced heat that would have kept the proto-stellar cloud of hydrogen and helium from cooling and shrinking and thus preventing fusion reactions from igniting. "The heating can counteract the cooling, and so the star stops contracting for a while, forming a dark star" some 80 million to 100 million years after the Big Bang.
. . These so-called dark stars would contain mostly normal matter, in the form of hydrogen and helium molecules, but would be vastly larger (about 400 to 200,000 times wider) and less dense than Sol and other stars.
. . It is conceivable that dark stars exist today, though they would not emit visible light. Instead they would produce gamma rays, neutrinos and antimatter such as positrons and antiprotons, Gondolo said.

Nov 30, 07: A leading model, called Cold Dark Matter cosmology, has seemed to suggest that there should be much more dark matter at the center of galaxies than observations actually show.
. . However, researchers using a supercomputer simulation of the early formation of a dwarf galaxy now argue that this may not be such a problem after all. In their simulation, they modeled the effects of early, violent interactions between gas clouds and dark matter. Much of the dense gas forms massive stars, which collapse and turn into supernovas –-and this process winds up explaining what we actually see in the universe.
. . "These huge explosions push the interstellar gas clouds back and forth in the center of the galaxy", said McMaster U research associate Sergey Mashchenko, the lead author of the study, in a statement. "Our high-resolution model did extremely accurate simulations, showing that this 'sloshing' effect --similar to water in a bathtub-- kicks most of the dark matter out of the center of the galaxy."

Nov 29, 07: Astronomers think they have found the two youngest planetary systems ever detected, where infant planets could be sweeping up dust and creating voids in protoplanetary disks 450 light-years from Earth.
. . NASA's Spitzer Space Telescope observed the ring-like gaps, which could signal the earliest signs of rocky planet formation around two young stars located in the constellation Taurus—UX Tau A and LkCa 15. Both stars are about 1 million years old, which is 10 times younger than other known planet-forming systems.
. . Espaillat's team saw ring-like gaps in the spinning planetary materials. "It's more like a lane has been cleared within the disk. The existence of planets is the most probable theory that can explain this structure", she said, as the lanes are likely too distant from the star to photoevaporate. The idea is similar to touching a dusty record as it rotates, clearing a ring in the mat of particles; planets, however, use their growing gravity to sweep up the dust.

Nov 28, 07: Young galaxies, so faint that scientists struggled to prove they were there at all, have been discovered by aiming two of the world's most powerful telescopes at a single patch of sky for nearly 100 hours.
. . An international group of researchers has identified 27 pre-galactic fragments, dubbed "teenager galaxies", which they hope will help astronomers understand how our own Milky Way reached adulthood.
. . "If you expose the image for long enough, you see fainter objects, such as these proto-galaxies. We took the largest telescope we could and stared through it for as long as we were allowed."
. . Light takes time to travel across the universe, and powerful telescopes can pick up light which reaches them from extremely far back in time. In this case, the ultra-long exposure technique allowed scientists to see back 11 billion years or more —-to 2 billion years after the Big Bang-— when galaxies were still forming. Scientists said the scope of the discovery was unprecedented.
. . Whether babies or teens, the clusters make a compelling case for the theory that galaxies formed bit by bit instead of all at once
. . It took Haehnelt and his colleagues five years to persuade the telescopes' managers to give them the chunk of time they needed to run their study, he said. It took another two years to gather the data, with scientists taking readings for one hour here, another hour there. The images were later superimposed electronically to create the full picture.

Nov 29, 07: One of the fastest moving stars ever seen is challenging theories to explain its blistering speed. The cosmic cannonball, a neutron star known as RX J0822-4300, was discovered with NASA's Chandra X-ray Observatory.
. . Astronomers used five years of Chandra observations to show that the rogue star is careening away from the Puppis A supernova remnant, leftovers of a star that exploded about 3,700 years ago. The neutron star is racing of our Milky Way Galaxy at about 4.8 million kph.
. . Other hypervelocity stars known to be exiting the Milky Way move at speeds about one-third as great -—likely shot toward interstellar space by an aggressive, supermassive black hole at our galaxy's center. In the case of RX J0822-4300, however, a tremendous lopsided supernova explosion rocketed the neutron star to its blinding speed. It has traveled 20 light-years thus far, and will take millions of years to escape the clutches of the Milky Way.
. . Despite using advanced computer models to simulate how such a stellar rocket could form, astronomers are at a loss of words.

Nov 21, 07: Wes Traub, an astronomer and project scientist for several proposed planet-finding NASA missions, would like to see extrasolar planets in greater detail than ever before. Traub and his colleagues envision blocking out the blinding light of distant stars with giant occulters, or "solar shades", to observe planets around stars with future space telescopes.
. . "There are many, many planets to be found", Traub said. If the solar shade idea takes off, he explained, astronomers could block the intense glare of a planet's star and precisely measure light reflecting off the planet. In effect, astronomers could look for life-nurturing compounds such as water, methane and oxygen on the planet.
. . "If we can image a planet with just one pixel on a detector ... we could characterize its surface and search for life", he said. If NASA approves such a mission in the next decade, JWST may be the first telescope to take such measurements.

Nov 21, 07: Eight unusual examples of a burned-out celestial object known as a white dwarf detected in our Milky Way galaxy represent a previously unknown category of stars, astronomers said.
. . White dwarfs mark the end point in stellar evolution for all but the most massive of stars in the universe, with about 97% of stars, including our sun, destined to finish their existence this way.
. . Previously known white dwarfs have fallen into two categories: those with a hydrogen-rich atmosphere and those with a helium-rich atmosphere. But Dufour and three other scientists described eight white dwarfs that break the mold by possessing carbon atmospheres.
. . The researchers think they may have formed from stars much more massive than the sun but not quite massive enough to explode as a supernova.

Nov 19, 07: Luna formed after a nasty planetary collision with young Earth, yet it looks odd next to its watery orbital neighbor. Turns out it really is odd: Only about one in every 10 to 20 solar systems may harbor a similar companion.
. . New observations made by NASA's Spitzer Space Telescope of stellar dust clouds suggest that moons like Earth's are —-at most—- in only 5 to 10% of planetary systems.
. . Shortly after Sol formed about 4.5 billion years ago, scientists think a vagrant planet as big as Mars smacked into infant Earth. The scenario is unique among other moons in the Solar System, which formed side-by-side with their planet or were captured by its gravity. Gorlova and her colleagues looked for the dusty signs of similar smash-ups around 400 stars.
. . Only one of all the stars they studied, however, displayed the telltale dust. The estimate, however, is possibly a generous one. "We don't know that the collision we witnessed around the one star is definitely going to produce a moon." So moon-forming events could be much less frequent than our calculation suggests." [& having a moon may increase the probability of higher lifeforms.]

Nov 14, 07: Small, rocky planets that could resemble the Earth or Mars may be forming around a star in the Pleiades star cluster (Subaru in Japanese), astronomers reported. One of the stars in the cluster, also known as the Seven Sisters, is surrounded by an extraordinary number of hot dust particles that could be the "building blocks of planets".
. . There is "hundreds of thousands of times as much dust as around our sun", said Benjamin Zuckerman, a UCLA professor of physics and astronomy. "The dust must be the debris from a monster collision, a cosmic catastrophe."
. . Located about 400 light years away in the constellation of Taurus, the Pleiades is one of the best known star clusters and among the closest to Earth. "The cluster actually contains some 1,400 stars", said Song.
. . Song said the dust can accumulate into comets and small planetisimal-size bodies, and then clump together to form planetary embryos, and finally full-fledged planets. "In the process of creating rocky, terrestrial planets, some objects collide and grow into planets, while others shatter into dust; we are seeing that dust."

Nov 11, 07: The universe just got a little bit slimmer. Revised calculations indicate the universe contains less normal and dark matter than previously thought, resulting in a "weight loss" of 10 to 20%.
. . Confirmation of the team's finding will have to await the launch of future space missions, Bonamente said, which can scan the skies for emission lines of normal matter more probingly.

Nov 9, 07: Somewhere out there, astronomers knew Sol had another long-lost relative aimlessly drifting through the Milky Way. Now they've found it. The star HIP 56948 is about 200 light-years away, now considered to be the best "solar twin" out of four known candidates. It may be a billion years older than Sol, which is middle-aged at 4.6 billion years.
. . The wayward star challenges the idea that our backyard star has a unique composition, as it has a similarly low quantity of the element lithium--a lightweight byproduct of the fusion reactions that power stars. Because of those observations, astronomers wondered if Sol's low amount of lithium was unique. The newfound twin now shows that it isn't.
. . Three other solar twins were previously proposed: 18 Scorpius, HD 98618 and HIP 100963. While similar to Sol in many ways, spectrographic analysis revealed that their lithium contents are dramatically higher.

Nov 8, 07: Ultra-high energy cosmic rays --particles that pack the punch of a rifle shot-- make their way to Earth from massive black holes in nearby galaxies, scientists said, in a finding that may solve a mystery that has puzzled physicists for decades.
. . This sub-atomic matter, they believe, likely breaks free just before stars, gas and dust are gobbled up by the gravitational pull of black holes. This begins to explain how a single particle carrying so much energy could make its way to Earth.
. . "This is a fundamental discovery", said Nobel physics laureate James Cronin of the University of Chicago. "The age of cosmic-ray astronomy has arrived."
. . Scientists have long suspected that ultra-high energy cosmic rays come from outside our galaxy, but researchers now believe they travel as far as 250 million light-years to Earth. "A single particle carries as much energy as a bullet from a rifle", added Katsushi Arisaka, a UCLA professor of physics.
. . Discovered 95 years ago, cosmic rays are not really rays at all but very energetic particles coming from space into the Earth's atmosphere. Most get their start in our galaxy, such as those from the Sun.
. . Ultra-high energy cosmic rays are most likely protons or other nuclei. These particles arrive on Earth once per square mile per century, making it highly unlikely one would ever hit a person.
. . When they reach the Earth's atmosphere, they start smashing into other particles and making new ones. "Each of these particles hits some other nucleus and produces more energetic particles", Kusenko said. "There is an avalanche-like process that results in a billion particles traveling at nearly the speed of light."
. . To trace the origins of the particles, the researchers used the Pierre Auger Observatory in Argentina, the largest cosmic ray observatory in the world, covering 1,200 square miles. It uses a network of 1,600 water tanks to capture the air showers. This allows the researchers to calculate the trajectory of the particles, which they matched up with a catalog of possible sources.
. . "The sources are the center regions of very active galaxies which host violent black holes" and are known as "active galactic nuclei", Mostafa said. "Now that we found the sources, we are one step closer to knowing what physical process can accelerate particles to these ultra-high energies. Right now, we don't know."
. . Where these cosmic "bullets" originated has been a source of much speculation, with scientists proposing everything from gamma ray bursts to decaying dark matter. Cosmic rays are thought to consist of protons and atoms stripped of their electrons.

Nov 8, 07: Three new planets discovered outside our solar system are among the hottest worlds ever found. The exoplanets were discovered by the Wide Angle Search for Planets (WASP) project, which is dedicated to the discovery of large gas planets that orbit very close to their stars. The stars scorch the planets, so they're called hot-Jupiters.
. . The gaseous worlds each orbit different Sol-like stars and were found using the so-called transit technique, whereby planets are detected by a slight dip in starlight caused by their passage directly in front of their parent star.
. . The newfound hot Jupiters orbit 20 to 40 times closer to their stars than Earth does the sun. The tight orbits mean the planets are tidally locked to their stars, the way the moon is to Earth, so that each constantly shows one face to the star, and that face is always hotter than the dark back side. With temperatures on their star-facing sides reaching upwards of 1,726 C, the new planets are "among the hottest found so far."
. . Unlike some hot Jupiters, the new planets don't seem capable of radiating away the heat from their stars. The influx of energy causes the planets to swell 25 to 50 times Jupiter's size, even though their mass is less than that of Jupiter.

Nov 6, 07: NASA scientists said they discovered a fifth planet orbiting a star and say the discovery suggests there are many solar systems that are, just like our own, packed with planets. The new planet is much bigger than Earth, but is a similar distance away from its sun, a star known as 55 Cancri.
. . Four planets had already been seen around the star, but the discovery marks the first time as many as five planets have been found orbiting a planetary system. Life could conceivably live on the surface of a moon that might be orbiting the new planet, but such a moon would be far too small to detect using current methods. "The star is very much like our own sun. It has about the same mass and is about the same age as our sun."
. . It took the researchers 18 years of careful, painstaking study to find the five planets, which they found by measuring tiny wobbles in the star's orbit. The first planet discovered took 14 years to make one orbit. The newly discovered planet has a mass about 45 times that of Earth and may resemble Saturn. It is the fourth planet out from the star and completes one orbit every 260 days --a similar orbit to that of Venus. "It would be a little bit warmer than the Earth but not very much." The planet is 72 million miles from its star --closer than the Earth's 93 million miles, but the star is a little cooler than our own sun.
. . "If there were a moon around this new planet ... it would have a rocky surface, so water on it in principle could puddle into lakes and oceans." But the moon would have to carry a lot of mass to hold the water.
. . "This discovery of the first-ever quintuple planetary system has me jumping out of my socks", Marcy added. "We now know that our sun and its family of planets is not unusual."
. . The inner four planets of 55 Cancri are all closer to the star than Earth is to the sun. The closest, about the mass of Uranus, zips around the star in just under three days at a distance of 3.5 million miles.
. . 55 Cancri is located 41 light-years away and is visible with binoculars. The system contains a clutch of four inner planets that are separated from an outer planet by a huge gap. Marcy said he's optimistic that continued observations will reveal a rocky planet around the star within five years. Such a potentially habitable planet could reside in the 1.1 million-km wide space that separates 55 Cancri's four inner planets and its outer one. "I would bet you that gap isn't empty", said study team member Debra Fischer of San Francisco State U. "What we see in our Solar System is that we are full up on planets. There are very few tiny windows where you can drop even a moon-sized object in and have it survive in a stable orbit.
. . Only one other star, mu Ara in the southern sky, is known to have four planets.

Nov 5, 07: Black holes often are thought of as just endless pits in space and time that destroy everything they pull toward them. But new findings confirm the reverse is true, too: Black holes can drive extraordinarily powerful winds that push out and force star formation and shape the fate of a galaxy.
. . "In the early universe, galaxies formed from clumps of gas coagulating from mutual gravitational attraction. If unhindered, they would have formed rather bigger structures than what we see today", said astrophysicist Andrew Robinson at the Rochester Institute of Technology in New York. "But if we take into account these winds blowing away surrounding gas, that could help explain the galaxy sizes we see."
. . Until now, scientists had only theorized that accretion disks launched these winds. No one had actually seen this happen. "These accretion disks are comparable in size to our solar system—big for us, but on the scale of galaxies they're really tiny, and far away to boot, making it virtually impossible to distinguish any details such as winds", Robinson said.

Nov 1, 07: Almost 20 years after it was first conceived, what will become the world's most powerful optical telescope is about to open its eyes. Lying beneath the clear skies of Arizona, the $120m (£55m) Large Binocular Telescope will allow astronomers to probe the Universe further back in time and in more detail than ever before.
. . Unlike most telescopes today, which consist of one light collecting mirror, the binocular telescope will consist of two 8.4m (27.5ft) discs used in tandem. This has been done before. For example, the now retired Multiple Mirror Telescope, also in Arizona, contained six mirrors each with a diameter of 1.8m.
. . It has the equivalent light-gathering capacity of a single 11.8m instrument and the resolution of an even bigger telescope. "It acts like a single telescope of 22.8m in diameter", said Dr Green. "That will give us a resolution which is 10 times greater than Hubble."
. . "The bubbling and windy air in the Earth's atmosphere creates distortions and blurs the stars", said Dr Green. "We need to un-blur them in order to combine both sides and make them work like one unit." To do this, the telescope has two secondary bowl-shaped mirrors, each 1.6 mm thick and covered with 672 magnets on the back. A computer analyses the light from a reference star and works out by how much the light has been distorted. The magnets then kick into action, changing the shape of the secondary mirror 1,000 times a second to correct for the atmospheric distortions.
. . The secondary mirrors will be delivered in 2008 and instruments that will take advantage of this so-called adaptive optics system will be up and running the following year.
. . One of those will be the LBT inferometer (LBTI). "It's designed as what's called a nulling inferometer that lets you reverse the phase of the light when it's combined so you cancel the light from a bright star and look for a faint planet next to a star."

Nov 1, 07: A massive explosion in the deep reaches of space stemmed not from one dying star, as is typical, but from two dead ones that collided as the climax of a long orbital dance, new research shows.
. . Two white dwarf stars slowly spiraled into each other to touch off a supernova explosion. A white dwarf is the remains of a star with too little mass on its own to end its stellar life as a supernova, the cataclysmic explosions that redistribute material back into space. The Sun, as well as stars with up to eight times its mass, will ultimately end up as white dwarfs.
. . Astronomers split supernovas into two categories: the explosion of a young, massive star whose core collapses, or the cataclysmic result of a white dwarf star siphoning gas from a stellar companion until it, too, blows itself apart.

Oct 29, 07: The heaviest "small" black hole ever has been discovered, and its mass of 24 to 33 times that of our sun defies current theories to explain its formation, scientists say. The new record setter, announced by NASA today, shatters an already puzzling weight record set earlier this month.

Oct 29, 07: Two Canadian astronomers think there is a good reason dark matter, a mysterious substance thought to make up the bulk of matter in the universe, has never been directly detected: It doesn't exist.
. . Dark matter was invoked to explain how galaxies stick together. Last August, an astronomer at the U of Arizona at Tucson and his colleagues reported that a collision between two huge clusters of galaxies 3 billion light-years away, known as the Bullet Cluster, had caused clouds of dark matter to separate from normal matter. Many scientists said the observations were proof of dark matter's existence and a serious blow for alternative explanations aiming to do away with dark matter with modified theories of gravity.
. . Now John Moffat, an astronomer at the U of Waterloo in Canada, and Joel Brownstein, his graduate student, say those announcements were premature. The pair says their Modified Gravity (MOG) theory can explain the Bullet Cluster observation.
. . Using images of the Bullet Cluster made by the Hubble, Chandra X-ray and Spitzer space telescopes and the Magellan telescope in Chile, the scientists analyzed the way the cluster's gravity bent light from a background galaxy—an effect known as gravity lensing. The pair concluded that dark matter was not necessary to explain the results. "Using Modified Gravity theory, the 'normal' matter in the Bullet Cluster is enough to account for the observed gravitational lensing effect."
. . Moffat compares the modern interest with dark matter to the insistence by scientists in the early 20th century on the existence of a "luminiferous ether", a hypothetical substance thought to fill the universe and through which light waves were thought to propagate.
. . "As far as we're concerned, [Moffat] hasn't done anything that makes us retract our earlier statement that the Bullet Cluster shows us that we have to have dark matter", Clowe said. "We're still open to modifying gravity to reduce the amount of dark matter, but we're pretty sure that you have to have most of the mass of the universe still in some form of dark matter."

Oct 25, 07: Hundreds of "missing" black holes have been found lurking in dusty galaxies billions of light-years away. "Active, supermassive black holes were everywhere in the early universe."
. . The finding, detailed in two studies, is the first direct evidence that most, if not all, massive galaxies in the distant universe spent their youths constructing supermassive black holes at their cores.
. . The new quasar-containing galaxies are all about the same mass as our Milky Way, but are irregular in shape. They are located 9 billion to 11 billion light-years away, so they existed at a time when the universe was in its adolescence: between 2.5 and 4.5 billion years old.

Oct 25, 07: An enormous cold spot in our universe could be explained by a cosmic defect in the fabric of space-time created shortly after the Big Bang, scientists say. If confirmed by future studies, the finding could provide cosmologists with a long-sought clue about how the infant universe evolved. But other scientists, and even members of the study team, are skeptical of the new claim.
. . Scientists think that shortly after the Big Bang, as the universe cooled and expanded, exotic particles transformed into the particles we know today via phase transitions similar to the gas-liquid-solid transitions that matter now experiences on Earth.
. . And like phase transitions on Earth, defects inevitably occur. When water crystallizes to ice, for example, cloudy spots appear in the ice that mark where water molecules are misaligned. Physicists predict that similar defects happened during the phase transitions of the early universe, and that the defects took different forms.
. . The team thinks a cold spot in the cosmic microwave background (CMB)—an energy artifact of the Big Bang that has been detected and mapped by NASA's Wilkinson Microwave Anisotopy Probe (WMAP) satellite—represents the most complex kind of cosmic defect, a 3-D blob-like structure called a texture.
. . Marcos Cruz of the Instituto de Fisica de Cantabria in Spain and colleagues analyzed the CMB cold spot, which spans 1 billion light-years across, finding it had properties consistent with a texture.

Oct 22, 07: A massive galaxy is stealing a billion suns worth of gas from a smaller galactic neighbor. In space, gas is a hot commodity. Really hot. In this case, about 730 C. And it's great for making new stars. "We may be viewing the larger galaxy in a rare, brief stage of its reincarnation from an old galaxy to a youthful one studded with brilliant stars."
. . They are close enough to perturb each other gravitationally and might eventually collide. Such galaxy mergers are common in the universe: Gas and stars in two nearby galaxies become tangled until they become one larger galaxy. The case of 3C 326 is the clearest example yet of large quantities of gas being heated and siphoned from one galaxy to another.

Oct 17, 07: A stellar black hole much more massive than theory predicts is possible has astronomers puzzled. Stellar black holes form when stars with masses around 20 times that of the sun collapse under the weight of their own gravity at the ends of their lives. Most stellar black holes weigh in at around 10 solar masses when the smoke blows away, and computer models of star evolution have difficulty producing black holes more massive than this.
. . The newly weighed black hole is 16 solar masses. It orbits a companion star in the spiral galaxy Messier 33, located 2.7 million light-years from Earth. Its also the most distant stellar black hole ever observed.
. . The findings could help improve formation models of "binary" systems containing a black hole and a star. It could also help explain one of the brightest star explosions ever observed.
. . The companion star of M33 X-7 passes directly in front of the black hole as seen from Earth once every three days, completely eclipsing its X-ray emissions. It is the only known binary system in which this occurs, and it was this unusual arrangement that allowed astronomers to calculate the pair's masses very precisely.
. . The tight orbits of the black hole and star suggests the system underwent a violent stage of star evolution called the common-envelope phase, in which a dying star swells so much it sucks the companion inside its gas envelope. This results in either a merger between the two stars or the formation of a tight binary in which one star is stripped of its outer layers. The team thinks the latter scenario happened in the case of M33 X-7, and that the stripped star explodes as a supernova before imploding to form a black hole.
. . While 16 solar masses is hefty for a stellar black hole, it is miniscule compared with the black holes thought to lie in the heart of many large galaxies. Such "supermassive" black holes have masses millions to billions times that of our sun, but they are thought to form by mechanisms different from the stellar variety.

Oct 12, 07: The switch has been thrown on a telescope specifically designed to seek out alien life. Funded by Microsoft co-founder Paul Allen, the finished array will have 350 six-metre antennas and will be one of the world's largest. The Allen Telescope Array (ATA) will be able to sweep more than one million star systems for radio signals generated by intelligent beings. Its creators hope it will help spot definite signs of alien life by 2025.
. . Rather than being hand built, each six-meter antenna is made of a mass-produced dish and off-the-shelf components. Behind the scenes, digital signal processing software is used to analyse data and clean out man-made interference.
. . The finished instrument will be able to study an area of the sky 17 times larger than that possible with the Very Large Array in New Mexico. It's expected to help improve understanding of such phenomena as supernovas, black holes, and exotic astronomical objects that have been predicted but never observed.

Oct 11, 07: Robert Quimby has an unusual distinction among astronomers. The Caltech postdoctoral researcher has discovered the two brightest star explosions ever witnessed within months of each other. Quimby's latest find is supernova 2005ap, which at its peak blazed 100 billion times brighter than the sun and was twice as luminous as the previous record holder, a supernova called 2006gy, which he also discovered. 2005ap was located 4.7 billion light-years away. The distance was crucial to determining the supernova's luminosity and establishing it as the brightest ever recorded.
. . It was speculated the parent star of that supernova was a stellar behemoth with about 150 times the mass of the sun, and that the explosion represented a new mechanism involving an exotic antimatter engine that had been theorized but never observed.

Oct 10, 07: Cosmic rays constantly bombard the Earth as tiny, extremely energetic particles traveling close to the speed of light, yet their origins have eluded scientists for nearly 100 years. A new study, however, brings the mystery a step closer to resolution.
. . Supernova remnants—the leftovers of massive stellar explosions—possess magnetic fields much stronger than previously thought, recent observations of pulsating X-ray hot spots reveal. Scientists said the discovery serves as some of the first direct evidence for a system powerful enough to accelerate particles into cosmic rays. "Magnetic field strength lies at the heart of cosmic-ray acceleration theory", said Yasunobu Uchiyama.
. . Since the 1960s, scientists have suspected supernova remnants as their breeding grounds. Such remnants travel through interstellar gas as they expand, producing high-speed shockwaves that can generate powerful magnetic fields. As protons, electrons and other charged particles from interstellar gas bounce around in the magnetic fields, they're accelerated to blinding speeds to create cosmic rays.
. . Cosmic ray factories in space work similar to Earth's particle accelerators, yet can pump particles with energies tens of thousands of times greater than the largest man-made machines. Until Uchiyama and his team's discovery, however, magnetic fields strong enough to create cosmic rays had never been directly detected.

Oct 9, 07: Like enormous jewel factories in the sky, the chaotic environments around some supermassive black holes crank out prodigious amounts of glass, rubies and sapphires, a new study finds. The inevitable breakdown of these materials into simpler components could account for much of the space dust in the universe -—dust that is recycled to make stars, planets, and life.
. . Traces of these minerals, as well as sand and marble, were recently found by scientists analyzing light from the region around a nearby supermassive black hole using NASA's Spitzer Space Telescope. The black hole was embedded in a quasar, a highly active and incredibly bright galaxy under construction. "We were surprised to find what appears to be freshly made dust entrained in the winds that blow away from supermassive black holes."
. . The finding could also help solve the mystery of where dust used to build the first generation of stars in the universe came from. The space dust in our corner of the universe is thought to have been created when ancient stars resembling massive versions of our sun exploded as supernovas at the ends of their lives. But when the universe was new, sun-like stars hadn't been around long enough to die and make dust. So where did the dust needed to make those stars come from?
. . One idea is that the dust came from quasars, which are supermassive black holes surrounded by dusty, doughnut-shaped clouds and lots of radiation. They are the most active, budding galaxies known, where gravity lures material in but the resulting pressure blows material away on a constant cosmic tug-of-war that results in high rates of star formation and the creation of new elements.

Oct 8, 07: The widely photographed and heavily studied Orion Nebula is nearly 300 light-years closer to Earth than previously thought, according to a new study. The finding also hikes up the age of the nebula's stellar inhabitants. "These stars are nearly twice as old as previously thought."
. . The scientists determined the distance to a star called GMR A, one of a cluster of stars in the Orion Nebula, by measuring the slight shift in the star's apparent position while the Earth was on opposite sides of its annual orbit around the sun. This technique uses called parallax.

Oct 8, 07: Dark matter is a mysterious something invoked by scientists to explain mass they know is out there but which can't be seen. The invisible matter, far more prevalent than regular matter, is evident by its gravitational effects on galaxies. And as researchers hunt for the strange stuff, they need not worry about it disappearing any time soon, if that makes any sense.
. . New calculations show at least 2.1 million- billion years must pass for half of the invisible stuff to decay, if it does at all. While all this theoretical thinking seems awfully abstract, it represents yet another effort to pin down what the heck dark matter might really be.
. . Scientists proposed the half-life—about 150,000 times longer than the current age of the universe—after looking at X-rays from the Bullet Cluster, a cosmic collision of galaxies thought to harbor two massive globs of dark matter.
. . If dark matter can slowly decay, it can also emit radiation, albeit at nearly undetectable levels. The proposed ultra-wimpy signal might help explain why it's practically invisible to our scientific instruments.
. . "We don't know what dark matter is, but we do know it's made of some kind of particle", said Signe Riemer-Sorensen, an astrophysicist at the U of Copenhagen in Denmark. "One theory says these particles are axions, which are very massive and can decay." Axion decay, she explained, is similar to radioactive decay of unstable elements, such as uranium-238. "But instead of different atoms, you get two photons we might detect as X-rays", she said.
. . The astrophysicists compared X-ray emission from one of the cluster's dark matter blobs to a desolate region nearby, but hardly any difference showed up. "We didn't see anything", she said, explaining that the dark matter blob had about the same amount of X-rays that the "control" region without any dark matter did. "This leads us to think dark matter must take a very long time to decay."
. . "There could be a weak X-ray emission from axion decay we aren't able to detect yet", she said, noting that more sensitive X-ray observatories are necessary to do so. "It's impossible to say it's not there until we have better instruments."

Oct 4, 07: Astronomers have spotted evidence of a second Earth being built around a distant star 424 light-years away.
. . Using NASA's Spitzer Space Telescope, astronomers have spotted a huge belt of warm dust swirling around a young star called HD 113766 that is just slightly larger than our sun. The dust belt, which scientists suspect is clumping together to form planets, is located in the middle of the star system's terrestrial habitable zone where temperatures are moderate enough to sustain liquid water. Scientists estimate there is enough material in the belt to form a Mars-sized world or larger.
. . At approximately 10 million years old, the star is just the right age for forming rocky planets. If the star system were too young, the planet-forming disk would be full of gas, and it would be making gas-giant planets like Jupiter instead. If it was too old, Spitzer would have spotted rocky planets that had long ago formed.
. . Earlier this year, scientists announced they had discovered one, and possibly two, already formed Earth-like planets around Gliese 581, a dim red star located only 20.5 light-years away. The planets, called Gliese 581c and Gliese 581d, are located at about the right distance from their star to support liquid water and life as we know it, but many more observations are needed to confirm this.
. . To date, planet hunters have discovered more than 250 extrasolar planets.

Oct 1, 07: Puffy debris disks around three nearby stars could harbor Pluto-sized planets-to-be, a new computer model suggests. The "planet embryos" are predicted to orbit three young, nearby stars, located within about 60 light years or less of the Solar System. AU Microscopii (AU Mic) and Beta Pictoris (Beta Pic) are both estimated to be about 12 million years old, while a third star, Fomalhaut, is aged at 200 million years.
. . If confirmed, the objects would represent the first evidence of a never-before-observed stage of early planet formation. Another team recently spotted "space lint" around a nearby star that pointed to an even earlier phase of planet building, when baseball-sized clumps of interstellar dust grains are colliding together.
. . The thickness of a debris disk depends on the size of objects orbiting inside it. The ring of dust thins as the star system ages, but if enough dust has clumped together to form an embryonic planet, it knocks the other dust grains into eccentric orbits. Over time, this can puff up what was a razor-thin disk.
. . The new model the researchers created predicts how large the bodies in a disk must be to puff it up to a certain thickness. The results suggest that each of the three stars studied harbors a Pluto-sized embryonic planet.
. . The circumstellar disk of Fomalhaut contains a void that scientists think is being cleared out by a Neptune-sized world. The researchers think the embryonic planets predicted by their model are too small to clear gaps like this in the disk.
. . All of the embryonic planets predicted to exist in the three systems are located far away from their parent stars. Au Mic's budding planet is estimated to lie about 30 AU from its star, or about the same distance that Pluto is from our sun. The embryonic planets of Beta Pic and Fomalhaut are thought to lie even farther, at 100 and 133 AU, respectively.
. . It is the large distances separating the planet embryos and their stars that have drawn the most criticism by colleagues, Quillen said. Many find it hard to believe that any planet, even a diminutive Pluto-sized one, could form at such a far distance. Sedna, for example, is about three-fourths the size of Pluto and is located about three times farther from the sun.
. . The criteria to be a candidate are strict. The systems have to be young enough to still have their circumstellar disks, but old enough to be forming embryonic planets. They must also appear edge-on as seen from Earth and be near enough that Hubble can accurately discern the thickness of their disks.
. . At the moment, the three stars Quillen has already observed appear to be the only candidates that meet all the standards.

Sept 27, 07: Astronomers who stumbled upon a powerful burst of radio waves said they had never seen anything like it before, and it could offer a new way to search for colliding stars or dying black holes.
. . They were searching for pulsars --a type of rotating compacted neutron star that sends out rhythmic pulses of radiation-- when they spotted the giant radio signal. It was extremely brief but very strong, and appears to have come from about 3 billion light-years away.
. . "This burst appears to have originated from the distant universe and may have been produced by an exotic event such as the collision of two neutron stars or the death throes of an evaporating black hole", said Duncan Lorimer of West Virginia U.
. . The burst appears to have lasted 5 milliseconds and may be the radio fingerprint of a single event such as a supernova or the collision of black holes, the astronomers said. "This burst represents an entirely new astronomical phenomenon."
. . Astronomers originally created the 480-hour-long observation to look for repetitive radio emissions from pulsars, which are thought to be fast-rotating neutron stars, but the event remained hidden in the data because no one had set out to find single bursts.
. . If the bursts are as frequent as Lorimer's team thinks, and they indicate the death of black holes or two super-dense neutron stars violently smacking together, a step toward closure of the universe's great mystery of gravity may soon come.
. . The dramatic cosmic events are predicted to let loose gravity waves that Einstein's theory of relativity predicts, but the phenomenon has never been directly observed. LIGO—the Laser Interferometer Gravitational Wave Observatory based in both Louisiana and Washington state—has been searching for such waves since it went online in 2002. The burst occurred about one year before the observatory began its scientific observations, so researchers can't look for it in old data.

Sept 25, 07: Black holes are weird enough. Breaking down known laws of physics to the point of unimaginable conditions qualifies as genuinely strange. But a team of Duke U and Cambridge researchers has now outlined a new twist on the theory, in which a fast-spanning black hole might shed some of the natural shields that keep scientists from observing it directly, becoming what they call a “naked” singularity.
. . The traditional model of black holes posits an object, such as a collapsed star, for which gravity is so strong that not even light can escape. The radius at which this effect begins –-the point beyond which the mass of the object twists space so completely that ordinary laws of physics break down-– is called the event horizon.
. . However, Duke professor Arlie Petters, working with Cambridge graduate student Marcus Werner, argue that a particular kind of black hole may not be entirely black after all, if certain conditions are met.
. . Non-spinning black holes don't seem to exist in nature. So he and Werner applied the analysis to singularities that might actually exist. They calculated that under some conditions –-those in which the angular momentum of the object exceeded its mass-– the effect could work. That would translate into rotations of a few thousand times per second for an object weighing 10 times more than the Sun, the researchers say.
. . Could such a thing actually exist, allowing scientists to probe the internal secrets of a black hole with instruments that exist now or in the near future? Possibly, but it's far from certain, the researchers say.

Sept 25, 07: Deer can't see cars at night because of blindingly bright headlights. And until now, astronomers couldn't see foreground galaxies outshined by the dazzling quasars behind them.
. . To locate the so-called "invisible" galaxies, Bouche and his team looked through huge catalogues of quasar data and picked out those with "dips" in their light signatures. Then, using the European Southern Observatory's (ESO) Very Large Telescope (VLT), located in the mountains of northern Chile, the team searched for galaxies close to the pulse of quasar light.
. . 70% of the time, they found a galaxy hiding in the "headlights" of a quasar. So far, the astronomers who pioneered the technique have detected 14 hidden galaxies.
. . Bouche said he is surprised by not only the amount of galaxies he and his colleagues have found hiding near quasars, but also by the types of these galaxies. "These are not just ordinary galaxies", he said. "They are ... actively forming a lot of new stars and qualifying as 'starburst galaxies.'" These types of galaxies are forming the equivalent of about "20 suns per year."

Sept 25, 07: Astronomers have yet to find an Earth-size planet beyond The Solar System, but that hasn't stopped them from modeling what these worlds might look like. A new catalog of 14 types of such planets, some fantastical, could help planet hunters spot what has until now remained fictional.
. . The computer models provide specs for 14 planet types, varying according to mass, diameter, composition and where the worlds could be found in our galaxy. Some are made mostly of pure water ice, carbon, iron, silicate, carbon monoxide or silicon carbide, while others are mixtures of these various compounds. "We're thinking seriously about the different kinds of roughly Earth-size planets that might be out there, like George Lucas, but for real", said Marc Kuchner of NASA
. . Rather than assuming faraway worlds around other stars would be big or small versions of planets in our solar system, the astronomers considered all possible types of planets given what they know about the composition of protoplanetary disks, the wells of raw material that form around young stars.
. . By modeling how gravity would compress a planet of a certain composition and mass, they predicted each planet's diameter, finding that no matter their composition, the planets followed a similar relationship between mass and diameter. "All materials compress in a similar way because of the structure of solids."
. . Sara Seager of MIT: "If you squeeze a rock, nothing much happens until you reach some critical pressure, then it crushes. Planets behave the same way, but they react at different pressures depending on the composition."
. . The team found a pure water planet weighing the equivalent of one Earth will span about 15,289 km, while an iron planet of the same mass will be compressed to a diameter of just 4,830 km. Earth, made up mostly of silicates, is 12,755 km across at its equator.

Sept 21, 07: A NASA mission to find black holes in our local universe has been restarted after cancellation early last year.

Sept 21, 07: An orbiting spacecraft has found evidence of what look like seven caves on the slopes of a Martian volcano, the space agency NASA said. The Mars Odyssey spacecraft has sent back images of very dark, nearly circular features that appear to be openings to underground spaces.
. . "They are cooler than the surrounding surface in the day and warmer at night. Their thermal behavior is not as steady as large caves on Earth that often maintain a fairly constant temperature, but it is consistent with these being deep holes in the ground."
. . The holes, which the researchers have nicknamed the "Seven Sisters", are at some of the highest altitudes on the planet, on a volcano named Arsia Mons. "Somewhere on Mars, caves might provide a protected niche for past or current life, or shelter for humans in the future."
. . But not these caves. "These are at such extreme altitude, they are poor candidates either for use as human habitation or for having microbial life", Cushing said. "Even if life has ever existed on Mars, it may not have migrated to this height." [Donno if that makes much diff. Mars atmo is near-vacuum anyway.]

Sept 20, 07: Orphaned stars are being born in a vast tail of material stretching behind a faraway galaxy, astronomers said. The finding is evidence that orphaned stars-those not orbiting the center of a galaxy in normal fashion-are much more common than thought.
. . The feature extends for more than 200,000 light-years and was created as gas was stripped from the galaxy. For comparison, our solar system is about 26,000 light-years from the center of the Milky Way, and we're said to be in the galactic outskirts. "This is one of the longest tails like this we have ever seen. And, it turns out that this is a giant wake of creation, not of destruction."
. . The observations indicate that the gas in the tail has formed millions of stars. Because the large amounts of gas and dust needed to form stars are typically found only within galaxies, astronomers had thought it unlikely that large numbers of stars would form outside a galaxy.
. . "If life was to form out there on a planet a few billion years from now, they would have very dark skies."

Sept 18, 07: Two dwarf galaxies thought to be our Milky Way's longtime companions are actually relative newcomers to our neighborhood that are just passing through, according to a new study.
. . The surprising finding is a celestial curveball of sorts, sending astronomers back to the clubhouse in order to rework theories that were based on long-lasting interactions between the Milky Way and the dwarf galaxies, called the Large and Small Magellanic Clouds. "We have known about the Clouds since the time of Magellan, and a single measurement has thrown out everything we thought we understood about their history and evolution," said the study's lead author, Gurtina Besla.
. . For instance, some astronomers thought a blazing trail of hydrogen gas extending from the Clouds, called the Magellanic Stream, formed due to tidal interactions between the Clouds and the Milky Way. Others explained the gas trail as the result of hydrogen being stripped from the Clouds by gas pressure as they plunged through the gas halo around our galaxy. Both scenarios are false if the galaxies are indeed just passing through.
. . Earlier this year, astronomers making the most detailed measurements yet of the 3-dimensional velocities of the Magellanic Clouds found they are flying through space twice as fast as previously thought.
. . Besla's team incorporated the new estimates into computer models, finding that both galaxies had extremely parabolic orbits and indicated they had entered our neighborhood for the first time between 1 billion and 3 billion years ago.

Sept 14, 07: A computer model of the early Universe indicates the first stars could have formed in spectacular, long filaments. These structures, which may have been thousands of light-years across, would have been shaped by "dark matter".

Sept 13, 07: A dead, spinning star has been found feeding on its stellar companion, whittling it down to an object smaller than some planets. "The pulsar has eaten away the star's outer envelope, and all that remains is its helium-rich core." Pulsars are the cores of burnt out "neutron" stars that spin hundreds of times per second.
. . The smaller companion orbits its parasitic companion from a distance of only about 230,000 miles--slightly less than the distance between the Earth and moon. It has an estimated minimum mass of only 7 times that of Jupiter, but it could be much larger. Unlike three Earth-sized objects found around a pulsar in 1992, scientists do not consider the new object to be a planet because of how it formed. "It's essentially a white dwarf that has been whittled down to a planetary mass."
. . Scientists think that several billion years ago, the system consisted of a very massive star and a smaller star about 1 to 3 times the mass of our sun. The bigger star evolved quickly and exploded as a supernova, leaving behind a spinning stellar corpse known as a neutron star. Meanwhile, the smaller star began to evolve as well, eventually puffing up into a red giant whose outer envelope encapsulated the neutron star. This caused the two stars to draw closer together, while simultaneously ejecting the red giant's envelope into space. After billions of years, little remains of the companion star, and it's uncertain whether it will survive.

Sept 10, 07: Small, ultrafaint "hobbit" galaxies recently found hovering around our Milky Way are comprised almost entirely of dark matter, a new study confirms.
. . The finding could help resolve a cosmic accounting problem that has long vexed astronomers and also explain how such small galaxies form. According to the "Cold Dark Matter" model, which explains the growth and evolution of the universe, large galaxies such as our Milky Way should be surrounded by a swarm of up to several hundred smaller "dwarf" galaxies. However, until recently, only 11 such companion galaxies have been found.
. . To explain this so-called Missing Dwarf Galaxy problem, theorists have suggested that the majority of dwarf galaxies contain very few, if any, stars and are instead made up mostly of dark matter.
. . Earlier this year, members of the Sloan Digital Sky Survey team announced they had discovered eight small and extremely faint galaxies in our Local Group of galaxies that might belong to this bizarre class of "dark" galaxies.
. . Using the Keck II telescope in Hawaii, Joshua Simon of Caltech and Marla Geha of the Herzberg Institute of Astrophysics in Canada conducted follow-up studies to calculate the mass of the hobbit galaxies based on the speeds at which stars inside them moved. The pair confirmed that each galaxy was among the smallest ever measured, more than 10,000 times smaller than the Milky Way. They also found that the mass of the galaxies was about 100 times more than what would be expected from the mass of their stars alone.
. . The researchers speculate that fierce ultraviolet radiation given off by the first stars, which formed just a few hundred years after the Big Bang, might have blown all of the hydrogen gas out of the still-forming hobbit galaxies. The loss of gas would have severely stifled future star formation, leaving the galaxies very faint or completely dark.
. . Simon estimates that scientists will need to find another 100 to 200 such galaxies to finally resolve the discrepancy between the number of predicted and observed dwarf galaxies.
. . This could prove difficult, however, since scientists predict that many dark matter galaxies do not contain any stars at all. One possible way to flush these invisible galaxies out might be to look for effects they have on our own galaxy.
. . Alternatively, some scientists speculate that dark matter particles can act like their own antimatter particles. When normal matter and antimatter collide, they annihilate each other and create a lot of energy. "Dark matter might do the same thing", Simon said. "You would see this as very high-energy gamma rays coming from these clumps of dark matter."

Sept 13, 07: Dark matter may have played a key role in forming the earliest stars, according to researchers who suggest that the mysterious and invisible material may also have been responsible for creating black holes. Their experiment offer clues to the universe just after the big bang some 13 billion years ago and indicates that dark matter helped set the thermostat on the first stars
. . As the universe initially was only helium and hydrogen, dark matter was critical in providing the gravitational force to pull these elements together to form stars. Now that there are other objects in the galaxy, dark matter is not needed to form stars.
. . Running computer simulations, the team found slow-moving, cold dark matter particles would have created one star at a time in isolation --generally a massive and relatively short-lived body at least 100 times the size of Sol.
. . In contrast, faster-moving warm dark matter would have created a large number of stars of all sizes in huge cosmic bursts that occurred in long , thin filaments of condensed gases. The researchers do not know which scenario played out, but said that either way, dark matter was key.
. . Stars formed in cold dark matter would be long gone, but smaller, slower-burning ones formed from warm dark matter could still be shining in the Milky Way, Theuns said.

Sept 13, 07: Astronomers have discovered the first known planet to survive its "red-giant" phase, a period when an aging star expands and engulfs bodies orbiting it.
. . The discovery of the gas-giant planet three times the size of Jupiter offers a look at the future of our own solar system and what will happen to the Earth when Sol grows old and collapses. It once orbited its star at the same distance as the Earth is now from Sol --about eight light-minutes-- but then drifted away.
. . The researchers said the planet stayed intact because the parent star lost mass, reducing its gravitational pull just enough to let the planet drift away a bit.
. . When Sol --which scientists think is 30% bigger than when it came into being --exhausts all its hydrogen and swells up during its red-giant phase, the Earth will also likely avoid complete destruction for the same reason, Kurtz said. "The future of the Earth is to die with the sun boiling up the oceans, but the hot rock will survive", he said.

Sept 6, 07: Astronomers have found nine of the faintest, tiniest and most compact galaxies ever seen. The little objects are hundreds to thousands of times smaller and vastly younger than our Milky Way, lending support to a "building block" theory in which hundreds of the tiny galaxies merge together and form larger bodies of stars. "These are among the lowest mass galaxies ever directly observed in the early universe." The two telescopes saw light emitted from the galaxies only 1 billion years after the theoretical Big Bang, giving a rare glimpse into the past.
. . The absence of infrared light in the sensitive Spitzer images showed the stars are first-generation and only a few million years old. "These are truly young galaxies without an earlier generation of stars", Malhotra said.

Sept 5, 07: A proposed NASA mission to study a mysterious force thought to be accelerating the expansion of the universe should be the first in the agency's "Beyond Einstein" program to be developed and launched, the National Research Council recommended today.
. . Beyond Einstein is NASA's research roadmap for five proposed space missions set to begin in 2009 that will study areas in science that build on and extend the work of physicist Albert Einstein. The missions include Constellation-X and the laser Interferometer Space Antenna (LISA), which will measure X-rays and look for hypothetical gravity waves, respectively, as well as the Inflation Probe (IP), the Black Hole Finder Probe (BHFP) and the Joint Dark Energy Mission (JDEM).
. . The National Research Council report recommended that JDEM be the first mission to be deployed since it is already in the prototype phase and will require less development than the other missions. "All of the mission areas in the Beyond Einstein program have the potential to fundamentally alter our understanding of the universe."

Aug 29, 07: Scientists looking at a fledgling Solar-type system have observed for the first time how water, considered a necessary ingredient for life, begins to make its way to newly forming planets. Its about 1,000 light years away.
. . NASA's Spitzer Space Telescope enabled them to find quantities of water vapor equal to five times the volume of all the oceans on Earth that had rained down onto a dusty disk around the star where planets are believed to form.
. . This solar system is forming inside a cocoon of gas and dust, within which is a big disk of planet-forming material. The observations, made using equipment on the Spitzer Space Telescope called an infrared spectrograph, indicate that icy material from this outer cocoon is in a supersonic free-fall, the scientists said. The ice vaporizes as it reaches the planet-forming disk.
. . Watson said the Earth's supply of water was delivered through collisions with icy planetisimals and comets. He said the water vapor seen in the distant solar system will freeze again into planetisimals and comets.

Aug 29, 07: Planet formation is a story with a well-known beginning and end, but how its middle plays out has been an enigma to scientists --until now. A new computer-modeled theory shows how rocky boulders around infant stars team up to form planets without falling into stars.
. . "This has been a stumbling block for 30 years", said Mordecai-Marc Mac Low. "The reason is that boulders tend to fall into the star in a celestial blink of an eye. Some mechanism had to be found to prevent them from being dragged into a star."
. . The solution: Together, many boulders can join to fight a cosmic headwind that otherwise would doom them. "Turbulence in the disk concentrates boulders in regions of higher pressure", Mac Low said, noting that such a disturbance is enough to enable the boulders to fight the dooming headwind. "If the gas is sped up, the boulders don't see a headwind. By getting the gas going with them they conserve energy and stay in orbit."
. . Mac Low compared the effect to a chain of semi-trucks driving down a highway. Each boulder is like a semi-truck "pushing" the gas in front of it, creating a friendly pocket of air behind it that other semis can travel in without using up as much fuel.

Aug 29, 07: Burning more brilliantly than a billion suns, the energy-packed star deaths known as supernovas have lately enabled scientists to discover fundamental properties of the universe.
. . Now physicists hope to uncover new cosmic secrets by recreating some supernova features in the lab. The REsonator SOLenoid with Upscale Transmission (RESOLUT) joins a small number of facilities around the world able to recreate some of the emissions and reactions of nature's biggest fireworks display. "We're doing experiments that replicate, in a very controlled manner, the explosions that take place in stars."
. . All Type 1a supernovas release virtually the same amount of energy, the observed brightness of such an explosion varies only with its distance from Earth, and so can be used as a gauge for measuring interstellar distances. "It is what astrophysicists call a 'standard candle' for mapping out distances", said Wiedenhöver. "At the same time they look at the observed redshift [which describes the supernova's velocity away from Earth] and measure the expansion of the universe."
. . "Not all Type 1a supernovae have exactly the same brightness", said Wiedenhöver. "Our effort is to make a model of brightness differences. To do this we need to understand the physics of the explosions." The reactions themselves are not well-studied, mainly because the highly unstable isotopes containing the radioactive nuclei are not found on Earth.

Aug 28, 07: Einstein's predicted warping of space-time has been discovered around neutron stars, the most dense observable matter in the universe.
. . The warping shows up as smeared lines of iron gas whipping around the stars, U of Michigan and NASA astronomers say. The finding also indicates a size limit for the celestial objects. The same distortions have been spotted around black holes and even around Earth, so while the finding may not be a surprise, it is significant for answering basic questions of physics.
. . "We're seeing the gas whipping around just outside the neutron star's surface", said XMM-Newton team member Edward Cackett of the U of Michigan. "And since the inner part of the disk obviously can't orbit any closer than the neutron star's surface, these measurements give us a maximum size of the neutron star's diameter." He said the neutron stars can be no larger than about 33 km across.

Aug 23, 07: - A giant hole in the Universe is devoid of galaxies, stars and even lacks dark matter, astronomers said. The team at the U of Minnesota said the void is nearly a billion light-years across and they have no idea why it is there.
. . "Not only has no one ever found a void this big, but we never even expected to find one this size", said astronomy professor Lawrence Rudnick. They were examining a cold spot using the Wilkinson Microwave Anisotropy Probe satellite, and found the giant hole.

Aug 22, 07: Scientists have unveiled a revolutionary camera capable of peering into the farthest reaches of space. The £14m Scuba 2 device has been developed by researchers at the Royal Observatory in Edinburgh. Astronomers hope the new camera, which is a thousand times more powerful than its predecessor, will enable them to explore distant undiscovered planets. The patented new technology could also have applications in fighting terrorism and detecting cancer. They hope to use it to compile a new atlas of the skies.
. . The camera is based on submillimeter astronomy, which is most sensitive to cold gas and dust. It uses a large-format array containing many thousands of pixels, which can instantaneously sample the sky.

Aug 17, 07: Observations of a distant galaxy cluster collision reveal a core of invisible matter devoid of glittering galaxies --something that is hard to explain by current theories. The invisible stuff is what astronomers call dark matter. They don't know what it is, but they know it exists because of its gravitational effects on normal matter and light.
. . If confirmed, the new results could force scientists to rethink their ideas about how dark matter behaves, or even conjure up a whole new class of dark matter. But scientists say they will await further confirmation before taking such radical steps.
. . "If it is confirmed, it may mean that dark matter is not really collisionless ... and can interact with itself", Loeb said, but "I think most people that work in this area would be cautious."

Aug 16, 07: Chemical elements observed around a burned-out star known as a white dwarf offer evidence Earth-like planets once orbited it, suggesting that worlds like our own may not be rare in the cosmos, scientists said. They studied a white dwarf called GD 362 located 150 light-years away.
. . They figured out the chemical composition of a large planetisimal that was ripped apart by gravitational forces as it approached GD 362, finding it was similar to the Earth's crust. It was rich in iron and calcium and low in carbon, much like a strong rock, they said. The white dwarf is surrounded by dusty rings, probably made up of objects shredded as they ventured too close.
. . GD 362 once was a star similar to Sol. After billions of years, it ballooned into a "red giant" as part of its death process, expelling most of its outer material, then degenerated into a burnt-out remnant called a white dwarf.
. . The fact that the planetisimal is so similar in make-up to the Earth, as well as Luna, indicates that rocky planets like our own may have orbited the star eons ago, Jura said. And if such planets currently populate our solar system and existed in a planetary system around this white dwarf, they may well be fairly common in the universe, Jura added.
. . The rocky planetisimal had a diameter of roughly 200 km and may have been smashed by GD 362 between 100,000 and a million years ago, the astronomers said. While the white dwarf has a mass close to that of our sun, it has collapsed to such a point that its diameter is approximately that of the Earth.
. . GD 362 may offer a glimpse into our solar system's future. Astronomers believe the sun in perhaps 5 billion years will go through the same process, ending up as a white dwarf.

Aug 16, 07: A large star in its death throes is leaving a huge, turbulent tail of oxygen, carbon and nitrogen in its wake that makes it look like an immense comet hurtling through space, astronomers said.
. . Nothing like this has ever previously been witnessed in a star, according to scientists who detected it using NASA's Galaxy Evolution Explorer, an orbiting space telescope that observes the cosmos in ultraviolet light.
. . This tail, spanning a stunning distance of 13 light-years, was detected behind the star Mira, located 350 light-years from Earth, moving at 130 km per second the star is spewing material that scientists believe may be recycled into new stars & planets.
. . "We believe that the tail is made up of material that is being shed by the star which is heating up and then spiraling back into this turbulent wake." NASA images show the tail as a glowing light-blue stream of material including oxygen, carbon and nitrogen.
. . This material has been blown off Mira gradually over time --the oldest was released roughly 30,000 years ago as part of a long stellar death process-- and is enough to form at least 3,000 future Earth-sized planet
. . 13 light-years is thousands of times the length of our solar system. The nearest star to Earth, called Proxima Centauri, is located 4 light-years away.
. . Mira is a so-called "red giant" star near the end of its life, & a so-called binary star traveling through space orbiting a companion believed to be the burnt-out, dead core of a star, known as a white dwarf. Scientists think Mira in time will eject all its gas, leaving a colorful shell known as a planetary nebula that also gradually will fade leaving behind a white dwarf.

Aug 10, 07: Extremely bright galaxies with accelerated star-birth activity have spotted lurking in the remote, young universe and are the most luminous and massive galaxies ever seen at that distance. The galaxies, located 12 billion light-years away, existed when the universe was less than 2 billion years old.
. . It's currently a mystery how such large, bright galaxies managed to form so shortly after the Big Bang. Most galaxies observed from that time are small and dim.
. . Stars in the galaxies form at a rate 1,000 times greater than in the Milky Way, making them intrinsically bright. However, much of their light has been missed until now because the galaxies are shrouded in thick clouds of dust and gas.

Aug 9, 07: Astronomers have spotted a small group of young stellar "siblings" in a dusty stellar nursery 848 light-years away. The finding, made using NASA's Spitzer Space Telescope, could reveal more clues about the formation of and interactions among cosmic families made up of hundreds of gravitationally bound stars.
. . "At visible wavelengths, the stars can't be seen at all; they are completely obscured by the dust in the cloud. This is the first time anyone has ever seen these stars." The recent detection of dusty clouds near a supergiant star provides the strongest direct evidence yet of why certain stars have mysterious periods of dimness.
. . They observed a massive cloud of dust particles 30 astronomical units (AU) away from the star RY Sagittarii. It is the closest dusty puff ever detected around a so-called R Coronae Borealis (R Cr B) star.
. . R Coronae Borealis stars are supergiants (more than 50 times the size of Sol) that exhibit erratic periods during which their brightness shrinks by a factor of 1,000 in just a few weeks, only to return to normal levels much more slowly. First observed in 1795, R Cr B stars have befuddled astronomers for ages.
. . The decades-old "Dust Puff Theory" holds that R Cr B stars sporadically eject matter, and that this matter can form carbon dust at a certain distance away, where the temperature is cool enough. If the carbon cloud meanders into our line-of-sight, the star is eclipsed and visible light waves are blocked. (Waves of higher frequencies, such as infrared, slip through the veil.) Then, slowly, the force of light particles pushes the darkening shroud away.
. . The astronomers reported the discovery of a cloud 100 stellar radii from the star's center, or 30 AU. However, the observed cloud is probably already six months old and far from its place of origin deeper within the stellar envelope. Further observations are necessary to determine which of several variations of the Dust Puff Theory explains the location of cloud formation.

Aug 6, 07: Four gigantic galaxies have been seen crashing into one another in one of the biggest cosmic collisions ever seen. A US team of astronomers observed the four-way cosmic smash-up using Nasa's Spitzer and Chandra space telescopes along with ground-based observatories.
. . The clashing galaxies are expected to eventually merge into a single, behemoth galaxy up to 10 times as massive as our own Milky Way. Dr Rines likened the collision to "four sand trucks smashing together, flinging sand everywhere". The new quadruple merger was discovered serendipitously during a survey of massive galaxy clusters consisting of tens to hundreds of galaxies.
. . "It will be one of the biggest ones in the Universe. This shows how these giant galaxies get assembled." All the galaxies in the merger are categorised as large; three are about the size of our own Milky Way, while the biggest one is about three times the size.
. . Analysis of the plume coming from the merger revealed it was made up of billions of stars flung out and abandoned in the ongoing clash. About half of the stars in the plume will later fall back into the galaxies. "There are more stars in that plume than there are in the Milky Way. So an incredible amount of material is being tossed out."
. . The Spitzer observations demonstrate that gas is a missing component in the new quadruple merger, perhaps explaining why only old stars have been found.

Aug 6, 07: The largest planet ever discovered is also one of the strangest and theoretically should not even exist, scientists say.
. . Dubbed TrES-4, the planet is about 1.7 times the size of Jupiter and belongs to a small subclass of "puffy" planets that have extremely low densities. "Its mean density is only about 0.2 grams per cubic centimeter, or about the density of balsa wood." "And because of the planet's relatively weak pull on its upper atmosphere, some of the atmosphere probably escapes in a comet-like tail."
. . It zips around its parent star in only three and a half days. The parent star of TrES-4 is also unusual in that it is about the same age as our sun but much farther along in its evolutionary history. "Because it is more massive, it has evolved much faster", Mandushev explained. "It has become what astronomers call a subgiant, or a star that has exhausted all of its hydrogen fuel in the core and is on its way to becoming a red giant. We actually looked at the energy which the planet gets from the star, and there's no way this can be the only explanation for how big the planet is."

Aug 2, 07: A planet outside our solar system with a year roughly equal to Earth's has been discovered around a dying, red giant star. It circles its bloated parent star every 360 days and is located about 300 light-years away. Only about 10 red giant stars are known to harbor planets; the new planetary system is among the most distant of these. The red giant star is twice as massive and about 10 times larger than Sol. Its planet is about the size of Jupiter or larger.
. . Our sun will become a red giant in a few billion years, likely vaporizing Earth. Sol's slow death will throw the orbits of the remaining planets out of whack. Some planets might collide with one another, and new ones could form from the resulting debris. And while all the organisms on Earth will have disappeared by that time, life could arise anew on other worlds in our solar system. Scientists speculate that there is more than enough time during a star's giant phase for life to evolve again. Now-frigid planets and moons in our solar system could become warm enough for life in the future.

July 31, 07: Some galaxies hide the normally bright output of supermassive black holes at their centers behind thick veils of dust and gas, a new study finds.
. . In the newly discovered type of "hidden" AGN (active galactic nuclei), the central black hole is so heavily shrouded by gas and dust that no visible light escapes. As a result, these galaxies are difficult to detect and were missed by previous AGN surveys.
. . Using NASA's Swift Telescope, Tueller and his colleagues spotted about 40 relatively nearby AGNs that were previously overlooked because their visible and ultraviolet light was dimmed by gas and dust. Swift uncovered the AGNs because the telescope can detect high-energy X-rays, which can pierce through the dust and gas.

July 25, 07: Astronomers have spotted a dusty disk in a four-star solar system that could be home to a planet in the making. Using the infrared eyes of NASA's Spitzer Space Telescope, astronomers spotted the swirling disk around a pair of stars in the quadruple-star system HD 98800, located 150 light-years away.
. . If a planet did form in the disk, its sky would be bathed in the light of four suns. One pair of suns would blaze brightly, while the other pair, gravitationally bound to the first pair, would appear as little more than faint pinpoints of light.
. . Most disks are smooth and continuous, but Spitzer detected a gap in the HD 98800 disk that could be evidence of one or more immature "protoplanets" carving out lanes in the dust. Alternatively, the researchers think the gap could be caused by a gravitational tug-of-war between the system's four stars. The other two stars are also doubled up, and the two binary pairs are separated by about 50 AU-slightly more than the distance between our sun and Pluto.

July 24, 07: Like gluttonous piranhas, supermassive black holes in young galaxy clusters gorge on bountiful gas until little fuel is left, and then they fade away, a new study suggests.
. . Using NASA's Chandra X-ray Observatory, astronomers tallied the number of rapidly growing supermassive black holes, called active galactic nuclei, or AGN, in two populations of galaxy clusters.
. . One group consisted of young-looking clusters located very far from Earth, and the other consisted of an older group located closer to us. The more distant, younger clusters contained about 20 times more AGN than nearer ones.

July 18, 07: Two galaxy clusters have been spotted colliding at what was previously thought to be impossibly high speeds. Astronomers estimate that the galaxy cluster collision known as Abell 576 involves two clusters-each containing hundreds of galaxies-crashing into one another at over 3,300 km/s (7 million mph).
. . While individual galaxies crash into one another fairly frequently, astronomers estimate that only one in a thousand to one in a hundred galaxy clusters are involved in a collision. The amount of energy generated by a single, major cluster collision is thought to be second only to the Big Bang event that scientists think gave rise to the universe.
. . Identifying colliding systems is crucial for understanding the makeup and workings of the universe. Scientists have cited evidence from cluster collisions as some of the best available yet that dark matter and dark energy really do exist. Also, if unrecognized, collisions can lead to an underestimation of galaxy clusters by as much as 20% because of the large amounts of gas ejected during a crash.
. . Scientists rely on the mass of various galaxy clusters to estimate the cosmological parameters describing the expansion of the universe.

July 17, 07: It is the rare gas giant planet that inhabits the outskirts of its solar system. Most are like our own Jupiter and prefer to stick close to their stars, a new study suggests. The finding helps give astronomers a better sense of how planets are arranged in the universe at large. "Now that we know there aren't large numbers of giant planets lurking at large distances from their stars, astronomers have a more complete picture and can better constrain [in theory and in models] how planets are formed", said study leader Beth Biller of the U of Arizona. Some planet formation theories have predicted that gas giants form far away from their stars and then migrate inward by gravitational interactions with other bodies.
. . They surveyed 54 nearby, young stars where gas giant planets would still be forming. Theory predicts young Jupiters are brighter and thus easier to spot than older gas giants.
. . The survey turned up no giant planets beyond 10 AU, leading the team to conclude that Jupiter-sized exoplanets are extremely rare in the outer parts of planetary systems.

Some recent studies, however, have suggested young gas giants might not be brighter than old ones as commonly thought. If this proves to be correct, it could mean remote Jupiters do exist but are just too faint to detect.

July 17, 07: Debris spots found on stars reveal planets that went splat like bugs on a windshield. The result: metal smears on the surface of parent stars. Stars that host planets are on average nearly twice as rich in metals than counterparts without worlds.
. . But are these stars rich in metals because planetary debris polluted them? Or do metal-loaded stars naturally spawn worlds? It's a classic chicken-or-egg problem. If these metals were planetary debris, they would only be found in the outer layers of stars. On the other hand, if these metals were inherently part of the stars, they would be found to their cores. Unfortunately, the only light that astronomers can see from stars comes just from their outermost layers, which means there is no direct way to peer into their hearts.
. . Instead, scientists looked at stars whose innards churn far more than our sun does. The ingredients of the interiors of these stars roil to their surfaces for astronomers to analyze.
. . Researchers focused on red giants --these giants have much larger convective zones, or regions where all the gas is completely mixed. The sun's convective zone comprises only 2% of the star's mass, but in red giants, the convective zone is 35 times more massive.
. . After inspecting 14 planet-hosting red giants, Pasquini and his colleagues found these were not rich in metals as is typically the case for planet-hosting sun-like stars. The simplest explanation is that metals seen in planet-hosting stars are pollution from planetary debris.

July 12, 07: "We have detected six faint star-forming galaxies", said graduate student Dan Stark. "We estimate the combined radiation output of this population could be sufficient to break apart the hydrogen atoms in space at that time, thereby ending the Dark Ages."

July 12, 07: Astronomers believe they've glimpsed light from some of the universe's first stars through the world's largest telescope on the Big Island. The astronomy team from the California Institute of Technology, which was to present its findings in London on Wednesday, said they used the Keck II telescope atop Mauna Kea volcano to see farther into space than ever before.

July 12, 07: Astronomers announced they had spotted the first planet beyond the Solar System that has water, the precious ingredient for life. The watery world, though, is far beyond the reach of our puny chemically-powered rockets --and in any case is quite uninhabitable. It is made of gas rather than rock and its atmosphere reaches temperatures hot enough to melt steel, which means the water exists only as superheated steam.
. . Extrasolar worlds are also called exoplanets. 245 of them have been spotted, according to the Extrasolar Planets Encyclopaedia (http://exoplanet.eu/), and the tally is growing at the rate of three or four a month.
. . Orbiting cheek by jowel to the star, at a distance that is 30 times closer than that between the Earth and the Sun, parts of the planet's atmosphere reach 2,000 degrees C. the other side of the planet is relatively balmy, with a low of 500 C.
. . The big prize is to spot a rocky planet that lies in the so-called Goldilocks Zone, where the temperature is not so hot that water evaporates, nor so cold that it is perpetually frozen, but "just right", enabling water to exist in liquid form.

July 12, 07: Scientists want Internet users to help them sort through an unusual digital photo album: pictures of about 1 million galaxies. In a Web statement Wednesday, astronomers asked for volunteers to help classify the galaxies, identifying them as either elliptical or spiral, and noting, where possible, in which direction they rotate.
. . It would the largest galactic census ever compiled, something scientists say would provide new insight into the structure of the universe.

July 10, 07: Astronomers using a giant telescope say they have found glimpses of the most distant --and oldest-- galaxies ever seen, a finding that will help provide clues to the origins of the universe.
. . The light the researchers viewed originated when the universe was only 500 million years old and has been traveling through distant space for billions of years, said Richard Ellis, an astronomer at the California Institute of Technology. The universe was born some 13.5 billion years ago.
. . The team used the giant Keck telescope in Hawaii, which boasts a light-gathering mirror measuring 10 meters in diameter. Ellis and his team were able to look even farther by pointing the telescope though a natural magnifying glass in space made up of much closer clusters of galaxies which deflected light and made it easier to see more distant bodies. It's known as "gravitational lensing". "We found areas of space which act as powerful magnifying glasses", he said. "Some of these places magnify the sky as much as 20 times."

July 9, 07: Stars form in cloudy nebulas and, shortly after genesis, consume most of the gas of their birthplace and use the surrounding dust and leftover gas to form planets, according to standard theory. The gas and dust collapse into a rotating "circumstellar" disk and are drawn toward the star. Planets are thought to sometimes migrate inward after birth, too. But scientists don't yet know what drives the inward spiraling motion.
. . A new model suggests magnetic instabilities in the disk cause gas to fall onto the star and also helps drag young planets into their final orbits. "Astronomers observe gas crashing down upon the surfaces of young stars by virtue of the ultraviolet radiation they emit, but a way to transport this gas from the disk to the star has not been convincingly specified", said study team member Eugene Chiang at the U of California, Berkeley.
. . The new model could also help explain why some planets outside our solar system orbit so close to their parent stars.
. . The magnetic instability arises from the fact that gas in the circumstellar disk orbits at different speeds depending on its distance from the star. Radiating throughout the disk like spokes on a bicycle wheel are magnetic field lines. Chiang likens the magnetic field lines to rubber bands binding the inner and outer gas rings together. Because the inner ring rotates faster than the outer one, the magnetic field "rubber bands" stretch in the direction of the rotation.
. . "What does that do? It pulls back on the inner ring and speeds up the outer one." This acts to slow down the inner ring, causing it to lose momentum and spiral inward to crash onto the star.
. . The new model suggests that planets riding the wave of inflowing gas toward the inner region of their planetary systems can be halted by magnetic instabilities in the immediate vicinity of the star. "Once disrupted, disk gas can no longer drag the planets inward", Chiang said.

July 3, 07: Using the largest telescopes available, astronomers have dissected the dusty, gassy layers of the red giant S Orionis-a star that pulsates in size from a diameter roughly equal to the orbit of Mars to that of Jupiter every 410 days. The information provides a glimpse at the future of our own sun, which will puff into a red giant like S Orionis in about 5 billion years.
. . "No study of a red giant has been done to this level, looking at infrared and radio-wave views simultaneously", Boboltz said. "This really shows us where the layers are."
. . Red giants are older versions of the sun that, once they have burned off most of their hydrogen fuel, begin to burn helium. This creates intense "flashes" of radiation that puff the star up to more than 100 times its original size as it pushes stellar gas and dust out into space. S Orionis sheds about the mass of Earth each year.

July 2, 07: It may be possible to glimpse before the supposed beginning of time into the universe prior to the Big Bang, researchers now say. Unfortunately, any such picture will always be fuzzy at best due to a kind of "cosmic forgetfulness."
. . The Big Bang is often thought as the start of everything, including time, making any questions about what happened during it or beforehand nonsensical. Recently scientists have instead suggested the Big Bang might have just been the explosive beginning of the current era of the universe, hinting at a mysterious past.
. . To see how far into history one might gaze, theoretical physicist Martin Bojowald at Pennsylvania State U ran calculations based on loop quantum gravity, one of a number of competing theories seeking to explain how the underlying structure of the universe works.
. . Past research suggested the Big Bang was preceded by infinite energies and space-time warping where existing scientific theories break down, making it impossible to peer beforehand. The new findings suggest that although the levels of energy and space-time warping before the Big Bang were both incredibly high, they were finite.
. . Scientists could spot clues in the present day of what the cosmos looked like previously. If evidence of the past persisted after the Big Bang, its influence could be spotted in astronomical observations and computational models, Bojowald explained. However, he also figures some knowledge of the past was irrevocably lost. For instance, the sheer size of the present universe would suppress precise knowledge of how the universe changed in size before the Big Bang, he said.
. . These findings differ from a cyclic model of the cosmos from cosmologist Paul Steinhardt at Princeton and theoretical physicist Neil Turok at Cambridge, which envisions an infinite series of Big Bangs preceding our universe caused by additional membranes or "branes" of reality perpetually colliding and bouncing off each other. Steinhardt said he felt Bojowald's calculations were concrete, but needed further elaboration to include the interplay of different kinds of matter and radiation.
. . Cosmologist Carlo Rovelli at the Center of Theoretical Physics in Marseilles, France, found it "remarkable" that the new work could delve past the Big Bang. He added the work had to lead to predictions that could be compared to cosmological observations "in order to become credible."

Jun 27, 07: Black holes are not the only objects in the universe that spew powerful jets from their poles. Dead, smoldering stars can emit them, too, and the jets they create rival and might even surpass those fired by black holes, scientists find.
. . The discovery, to be detailed in an upcoming issue of The Astrophysical Journal Letters, shows that the unusual properties of black holes --like the presence of an event horizon and the lack of an actual surface-- are not required for jets to form. "Gravity appears to be the key to creating these jets, not some trick of the event horizon." The Circinus X-1 jet is the first extended X-ray jet associated with a neutron star.
. . Heinz and his colleagues estimate that a surprisingly high percentage of the energy created by material falling onto the neutron star is used to power the jet.

Jun 26, 07: The skies of stars might experience weather like that on planets, researchers now find. The drifting clouds scientists have seen are wispy, "just like cirrus clouds on Earth" --except these are made of mercury! Investigating these metal clouds might shed light on how elements form inside stars.
. . Kochukhov and his colleagues spent seven years peering at alpha Andromedae, the brightest star in the Andromeda constellation. The bluish-white star lies about 100 light-years from Earth and is more than twice as hot as the Sun and roughly three times its mass and diameter.
. . Alpha Andromedae is not magnetic, so the spots Kochukhov and his colleagues discovered on it five years ago were an enigma. Now the researchers find these spots are clouds in that form and disperse, following dynamics similar to weather patterns on planets.
. . Such weather could be seen on stars that, like alpha Andromedae, are hot and massive. They also have to spin relatively slowly-alpha Andromedae completely rotates about once every 60 hours-as spinning too fast might destroy any clouds. Kochukhov noted a half-dozen or so other candidates have recently been seen already, including the star AR Aurigae, which might have clouds of strontium, yttrium and platinum as well.

Jun 19, 07: Scientists earlier this year announced they had found a small, rocky planet located just far enough from its star to sustain liquid water on its surface, and thus possibly support life.
. . Turns out the scientists might have picked the right star for hosting a habitable world, but got the planet wrong. The world known as Gliese 581c is probably too hot to support liquid water or life, new computer models suggest, but conditions on its neighbor, Gliese 581d, might be just right.
. . Gliese 581c is about 50% bigger than Earth and about five times more massive. But new simulations of the climate suggest the planet is no Earthly paradise, but rather a faraway Venus, where CO2 and methane in the atmosphere create a runaway greenhouse effect that warms the planet well above 212 degrees Fahrenheit (100 Celsius), boiling away liquid water and with it any promise of life.
. . But the same greenhouse effect that squashes prospects for life on Gliese 581c raises the same hope for another planet in the system, a world of eight Earth-masses called Gliese 581d, which was also discovered by Udry's team. "This planet is actually outside the habitable zone", said Manfred Cuntz, an astronomer at the U of Texas at Arlington and a member of von Bloh's team. "It appears at first sight too cold. However, based on the greenhouse effect, physical processes can occur which are heating up the planet to a temperature that allows for fluid water."
. . The stability of the light also suggests Gliese 581 is old and that is has been around for at least a few billion years. "We know it took about three and a half billion years for life on Earth to reach the level of complexity that we call human", Matthews said, "so it's more encouraging for the prospects of complex life on any planet around Gliese 581 if it's been around for at least as long."

Jun 15, 07: Two explosions observed in 2004 and 2006 in a galaxy (far, far away...) 78 million light years from Earth, were part of the fiery death of one of the most massive stars known to exist, astronomers said. Scientists described the supernova death of a star estimated to be 50 to 100 times as massive as our sun in a galaxy called UGC4904
. . This marked the first time a double explosion like this has been observed, adding to the understanding of the life cycle of stars.

Jun 11, 07: Alien worlds, once hidden from knowledge, are now being discovered in droves, stunning astronomers with their unique features and sheer numbers. The discoveries are so common that more and more don't even get reported outside scientific circles.
. . Take the announcement at the end of May of a massive planet, dubbed TrES-3, that zips around its star in an amazingly rapid 31 hours, giving the planet a 1.3-day year.
. . The regularity of planet finds, luckily, is buffered by the wild variety in the discoveries themselves, including the following contrasts: nascent worlds of just a million years versus those that are billions of years old; hot gas giants and icy Neptune-like orbs; planets that whip around their parent stars with cosmic speed and others that seem to creep at a slug's pace; and planets orbiting double-stars, red-dwarf stars and even so-called failed stars.
. . While the "transit method" provides astronomers with the best indirect information about an exoplanet, so far only about 20 transiting planets have been spotted. That's why the most successful (based on the number of planet finds) teams have relied on the so-called wobble method, or radio-velocity technique.
. . * Longest orbit: HD 154345 b takes 13,100 days to orbit its parent star.
. . * Lightest planet: Gliese 581 C weighs just five Earth masses.
. . So far, about 25 multi-planet systems have been identified with two such systems supporting four planets.

Jun 7, 07: The most distant black hole ever found is nearly 13 billion light-years from Earth, astronomers announced. The Canada-France-Hawaii Telescope spotted the bright burst of light the black hole created as it sucked up nearby gas, heating it and causing it to glow very brightly in what's known as a quasar. The distance to the quasar was determined by measuring the amount of redshift.
. . Astronomers are seeing the quasar as it appeared a mere 1 billion years after the Big Bang, which gives them a unique view into universe's past. "It is puzzling how such enormous black holes are found so early on in the universe ... because we believe that black holes take a long time to grow."

Jun 4, 07: Astrophysicists have found a star-like object with a surface temperature just one tenth that of the Sun. The cold object is known as a brown dwarf.
. . This one - called J0034-00 - is thought to have a surface temperature of just 600-700 Kelvin (up to 430C/800F). It is the coldest solitary brown dwarf ever seen, according to the British team.
. . This find further tests the boundary between high-mass gas planets and the smallest brown dwarfs. "Physically, stars, brown dwarfs and the gas planets are all the same thing - they're just blobs of gas with different mass", said Dr Steve Warren, of Imperial College London, who led the project. "And as this work progresses, we're going to start finding things between the stars which have the masses of planets, and what are we going to call them?" It has a mass of just 15-30 times that of Jupiter, and a similar diameter.
. . It could be about 50 light-years away. That is not far, compared with the distance from some of the stars that can be seen with the naked eye.

Jun 1, 07: The first image of the surface of a Sun-like star has been captured. It confirms that Altair, one of the brightest stars in the night sky, is a rapidly spinning, non-spherical body. Previous research had suggested that this bright star was spinning very rapidly - about 60 times faster than our home star.
. . Professor Monnier said: "Even Altair, which is pretty close at 15 light-years away and very bright, would be very challenging to zoom-up on. In order to do this, you would need a telescope that is about 300m across --and that is a long way beyond our engineering capabilities." They got around this problem by combining the light from four separate telescopes.

Mar 30, 07: Newly discovered stellar streams that arc around our galaxy might be the remnants of cannibalized star clusters and galaxies, scientists announced. They compare the colors and luminosities of stars and grouping similar stars together. The stellar streams findings reveal our galaxy can be a dangerous place for passersby, said researcher Carl Grillmair of Caltech.
. . Stellar streams are thought to form over billions of years as our galaxy's gravity slowly tears apart globular clusters and even dwarf galaxies. The stars, which were once packed tightly together, are now separated by light-years, trailing one another as they jet at high speeds through the galactic halo.
. . Two of the discovered streams are about 13,000 light-years from Earth and are likely the remains of ancient globular clusters, spherical collections of hundreds of thousands of old stars. Astronomers have identified only about 150 globular clusters orbiting the Milky Way, though they think thousands may have existed in the past.
. . The third stream is about 130,000 light-years from Earth and could be the closest dwarf galaxy to our Milky Way ever discovered. To date about 20 dwarf galaxies have been identified in the Milky Way and astronomers have wondered why they haven't found more.
. . Containing up to 100 million stars, dwarf galaxies are also thought to be chock-full of dark matter, the glue thought to hold our galaxy together. Grillmair suspects stellar streams will garner loads of scientific attention for years to come, as they are windows into our galaxy's past, present and future and likely hold evidence of dark matter.
. . One theory for how our galaxy formed says that lots and lots of dwarf galaxies merged, and are continuing to merge, and ultimately gave rise to the Milky Way. The dwarf-galaxy stream could be one such merger that's slowly succumbing to the Milky Way's gravitational lure.

May 29, 07: One of the exoplanets, orbiting a red M dwarf just 30 light-years from Earth, was discovered two years ago, but recent observations have allowed astronomers to pin down its mass, radius and density. The ice-giant planet circles the star Gliese 436 (GJ 436) and has a radius and density that are surprisingly similar to that of Neptune. Weighing in at 22.4 Earth-masses, the exoplanet is the first Neptune-sized planet observed to transit a star.
. . At least four of the newly spotted planets belong to multiple-planet systems, supporting the idea that at least 30% of all planet-parent stars have more than one planetary companion. Since smaller planets and those outside our solar system are trickier to detect, Wright predicts this percentage will continue to rise as detection methods improve.

May 28, 07: Planet-seekers who have spotted 28 new planets orbiting other stars in the past year say The Solar System is far from unique and there could be billions of habitable planets. The most recent planet discoveries bring the number of known exoplanets --planets outside the Solar System-- to 236.
. . "Our Milky Way galaxy has 200 billion stars. I would estimate that 10% of them, perhaps, have planets that are habitable", Marcy said. "There are hundreds of billions of galaxies, all of which are more or less like our Milky Way Galaxy, which is tens of billions of planets like our own."
. . There is one unusual property to the Solar System: the nearly circular orbits of the planets, which gives a consistent dose of radiation from the Sun. Other planetary systems seen so far are not usually like this. "Most of the planets are not in circular orbits around the host star but in elongated ones. An elongated orbit could not sustain life."

May 28, 07: A "failed star" with only 24 times the mass of Jupiter is the smallest known object to spout jets of matter from its poles, a phenomenon typically associated with much larger black holes and young stars.
. . The new finding confirms that a wide range of celestial objects is capable of generating such outflows. "There are black holes that are 3 million solar masses spewing jets, and there's this thing, which is 2% of a solar mass, doing the same thing."
. . The discovery also raises the possibility that large gas giant planets like Jupiter or Saturn might also have been gushers some time early in their history.
. . Called 2M1207a, the spurting brown dwarf is ringed by gas and dust, similar to the protoplanetary disks from which planets form around young stars. Indeed, 2M1207a is known to harbor a 5-Jupiter-mass planetary companion. Called 2M1207b, the gas giant was one of the first planets outside of our solar system to have its picture taken directly. The jets extend about 1 billion km into space and are speeding away from the brown dwarf at a few kilometers per second.
. . Another hypothesis is that jets actually play a major role in initiating star formation in the first place. Stars are thought to form from enormous, spinning clouds of gas and dust that somehow collapse and contract into blazing balls of fire. To do this, the clouds must get rid of a lot of spin energy, or "angular momentum." "It seems like almost any time you have accretion disk around an object, some of the material that's accreted is also spewed out."

May 24, 07: Like well-prepared travelers, some wandering black holes take their food with them as they journey through --or even beyond-- their host galaxies. Some supermassive black holes at the centers of large galaxies are thought to be ringed by swirling belts of hot gas, called "accretion" disks, upon which they feed. Black holes that have large quantities of matter falling into them in this way are called "quasars".
. . When two large galaxies merge, their black holes also coalesce. If the black holes have unequal masses, their merger causes powerful gravitational radiation to be emitted in a single direction. Like a mighty shotgun blast, the "radiation kick" causes the black hole or quasar to recoil, at speeds of up to 16 million km/h --a displaced quasar.
. . Despite recent advances in computer modeling of black-hole mergers, it was unclear whether recoiling quasars could hang on to their accretion disks (the food) during ejection from the galactic center. New calculations by Loeb suggest they can. Loeb predicts that so long as the accretion disk spins around a black hole faster than the black hole's ejection speed, the disk will follow the black hole on its journey. This is an easy requirement for most quasars, the accretion disks of which can spin at close to the speed of light.
. . Loeb estimates a displaced quasar can travel about 30,000 light-years from its galactic center before exhausting its accretion disk. Without a steady food supply, the quasar stops radiating energy and becomes a quiescent black hole.
. . If a wandering black hole is not traveling at high enough speeds to escape its host galaxy entirely, it will eventually fall back to the galactic center in about 100 million years, Loeb said.

May 23, 07: Any galaxies outside of our own cluster will disappear in about 100 billion years. Future observers will be clueless that their universe is still expanding. "It will be a sort of twisted situation, where thinking returns to what it was at the turn of the 20th century." Observers will think the universe is just a static--or non-expanding--cluster of galaxies just as scientists thought until the 1920s.
. . An additional issue for future observers will be the disappearance of cosmic microwave background radiation --the fingerprint of the Big Bang's occurrence-- in about 250 billion years. Without it, Krauss said, observers can't be certain about how the universe was created, not to mention when.
. . The problem relates to the Doppler effect: When a speeding train approaches, the sound waves from its whistle are squished together to make a higher pitch. As it passes, the sound waves are stretched out like a slinky and become lower in pitch and fainter. Similarly, as the universe expands outward, the "pitch" of light will lengthen and fade away. "The wavelength of light will be so large it will eventually reach the size of our galaxy", Krauss said. "It will just be absorbed."

May 22, 07: New research into the chemical composition of stars could identify our Sun's long lost family and begin to unravel the complex history of our galaxy.
. . Gayandhi De Silva and colleagues at the European Southern Observatory's Very Large Telescope (VLT) used the instrument's Ultraviolet and Visual Echelle Spectrograph (UVES) to examine three open star clusters in our Milky Way galaxy.
. . Open clusters are loosely gravitationally bound groups containing up to a few thousand individual stars. These clusters formed from the collapse of a giant molecular cloud of gas and can have ages up to 10 billion years.
. . Our Sun was born in an open cluster some 4.6 billion years ago, growing alongside its sibling stars like grapes on a vine, theorists say. Meteorites hold evidence for this close companionship in that they contain traces of the radioactive decay of the isotope Iron-60 which is only produced when a large star explodes in a supernova.
. . The VLT data obtained by De Silva has now confirmed the stars in each open cluster have their own distinctive "flavor": the same chemical composition. Such chemical homogeneity is expected if all the stars are formed together within the same parent gas cloud", De Silva said. This chemical resemblance between the clusters constituent stars indicates that the original gas cloud from which the stars formed was well mixed prior to star formation.
. . These stars lost touch with our own billions of years ago when our unstable open cluster dispersed, but these stars cannot conceal their roots. "The elemental abundances of these stars are preserved despite the star cluster being kinematically dispersed. With detailed high accuracy measurements we should be able to find the chemical signatures of dispersed clusters that are otherwise unidentifiable. If one can find other such stars that match the age and exact chemical composition of the Sun, it is very likely they have been born alongside the Sun."
. . "To do this sort of "chemical tagging" we need to have quality high resolution spectroscopic data. The upcoming ESA's GAIA mission will surely give a boost to testing these techniques, plus future high efficiency spectrographs on Extremely Large telescopes will also provide much of the required data", De Silva said.

May 18, 07: Scientists have pinpointed the precise locations of a pair of supermassive black holes at the centers of two colliding galaxies 300 million light-years away.
. . Infrared images made by the Keck II telescope in Hawaii reveal the two black holes at the center of the galaxy merger known as NGC 6240 are each surrounded by a rotating disk of stars and cloudy stellar nurseries.
. . Images captured by the Hubble Space Telescope showed the outer parts of the colliding galaxies in visible light, and revealed long tidal tails made of orphaned stars, gas, and dust. Subsequent X-ray observations by NASA's Chandra X-ray Observatory revealed the presence of two supermassive black holes at the center of each galaxy, and the Very Long Baseline Array spotted two radio sources in the galaxies' central regions. The problem was combining all of the images to form a single coherent picture.
. . Like a Rosetta Stone, the Keck II images allowed scientists for the first time to calibrate the different images of NGC 6420. "Now we can really see it all-the hot dust in the infrared, the stars in the visible and infrared, and the X-rays and radio emissions from right around the black holes."
. . Scientists think galactic mergers are one of the primary ways galaxies form. Like heated wax in a lava lamp, two small galaxies can come together to form one larger one, or a blob of gas and stars might pinch off during a particularly messy galactic smash-up and, over cosmic time, the result evolves into a diminutive dwarf galaxy.
. . Scientists estimate the two black holes in NGC 6240 will spiral into each other and merge in 10 million to 100 million years.

May 16, 07: An odd planet the size of Neptune, made mostly of hot, solid water, has been discovered orbiting a nearby star and offers evidence that other planets may be covered with oceans, European astronomers reported. The planet orbits quickly around a cool, red star some 30 light-years away.
. . The astronomers estimate its temperature at 247 degrees C. The planet is hot because it is near its star and under high pressure because of its mass. "The water is frozen by the pressure but it's hot. It's a bit strange -- we are used to water changing conditions because of temperature, but in fact water can also be solidified by pressure", Pont said.
. . The planet is also likely blanketed by hydrogen, the researchers said --conditions hardly conducive to life. But if there is water, there could be water on other planets in other planetary systems, and thus life as we know it. "It shows there are many ocean planets", Pont said. "When it passes in front of the star it is like a mini eclipse", Pont said. "The amount of light that it hides is proportional to its size."
. . Many appear to be gas giants like Jupiter. This one appears to be smaller, but not small enough to have a rocky center as the Earth does. "From the size and the mass, we get the density", Pont said. And the density of GJ 436b suggests it is made of water. "The mass and radius that we measure for GJ 436b indicate that it is mainly composed of water ice. It is an 'ice giant' planet like Uranus and Neptune rather than a small-mass gas giant or a very heavy 'super-Earth', the researchers wrote. "It's a small star, 100 times less bright than the sun", Pont said. It is about half the sun's mass.

May 15, 07: Astronomers have found one of the best pieces of evidence for the existence of dark matter. They have identified what appears to be a ghostly ring in the sky which is made up of this enigmatic substance.
. . Using the Hubble Space Telescope, the scientists have established that the ring formed long ago after a colossal smash-up between two galaxy clusters.
. . Astronomers have long suspected the existence of this invisible "stuff" as the source of additional gravity that holds together galaxy clusters. The clusters would fly apart if they were reliant only on the gravity from their visible stars. No one knows what dark matter is made of, but it is thought to be a type of elementary particle found throughout the cosmos.
. . Researchers spotted the ring unexpectedly while they were mapping the distribution of dark matter within the galaxy cluster Cl 0024+17. This cluster lies 5 billion light-years from Earth; its ring of dark matter measures 2.6 million light-years across.
. . Because astronomers cannot see dark matter, they must infer its existence by studying how its gravity bends the light of more distant, background galaxies. "By seeing a dark-matter structure that is not traced by galaxies and hot gas, we can study how it behaves differently from normal matter."
. . Computer simulations of galaxy cluster collisions show that when two clusters smash together, the dark matter falls to the center of the merged cluster and sloshes back out. As the dark matter seeps outward, it begins to slow down under the pull of gravity and gathers together like a traffic pile-up. Luckily, astronomers had a head on view of this collision because it occurred along the Earth's line of sight.

May 15, 07: The solar system might get booted from the suburbs to the boondocks of our galaxy when the Milky Way merges with its neighbor Andromeda in a few billion years, scientists say.
. . New calculations by T.J. Cox and Avi Loeb of the Harvard-Smithsonian Center for Astrophysics show there is a small possibility that the Sun and its planets will be exiled to the outer reaches of the merged galaxy. Computer simulations by Cox and Loeb suggest the Milky Way and Andromeda will make their first close pass in about 2 billion years. The two galaxies, currently separated by about 2.2 million light-years, are rushing towards each other at about 310,000 mph (500,000 kph).
. . During that first close encounter, the two galaxies will circle around each other a few times and their stars will begin to intermingle. The Sun at that time will still be a hydrogen-burning main-sequence star, but it will have brightened and heated enough to boil away the Earth's oceans, other studies predict.
. . The new computer model finds there is a 12% chance that during this first brush between Andromeda and the Milky Way, the Sun will be pulled from its present position into a "tidal tail", a streamer-like cluster of orphan stars stripped from their parent galaxies. After the galaxies circle each other a second time, there is a 3% chance our Sun will be more tightly bound to Andromeda than the Milky Way.
. . In 5 billion years, Andromeda and the Milky Way will have completely merged to form a single, football-shaped elliptical galaxy. Loeb jokingly calls this future galaxy "Milkomeda".
. . When the two galaxies finally merge, the Sun will be an aging star on the verge of inflating into a red giant. According to the new computer simulations, the Sun and its planets will get pushed out to 100,000 light-years from the center of the new galaxy-4 times farther than the current 25,000 light-year distance.

May 11, 07: Long before the Solar System formed and even before the Milky Way assumed its final spiral shape, a star slightly smaller than Sol blazed into life in our galaxy, formed from the newly scattered remains of the first stars in the universe.
. . Employing techniques similar to those used to date archeological remains here on Earth, scientists have learned that a metal-poor star in our Milky Way called HE 1523 is 13.2 billion years old --just slightly younger than 13.7 billion year age of the universe. The Solar System is estimated to be only about 4.6 billion.
. . Like other early stars, HE 1523 contains very few elements heavier than hydrogen or helium. But it does have some. In particular, it contains radioactive metals such as uranium and thorium. If scientists know an element's half life and the amount of the original sample, they can estimate an object's age based on how much of the element is left. Uranium and thorium have half-lives of 4.7 billion years and 14 billion years, respectively. This same technique is used with a radioactive form of carbon, called carbon-14, to date fossils rocks and archeological remains.
. . The uranium and thorium in HE 1523 were probably leftover elements from first generation stars that exploded as supernovas and scattered their atomic ashes through space. Second generation stars like HE 1523 formed from those strewn elements.
. . Because the uranium and thorium were formed during the supernova explosion of another star, what the researchers really dated was the age of the supernova. But, as Frebel notes, "the time between the supernova and [the birth of HE 1523] is relatively short compared to the age of the star."
. . Scientists think the first stars in the universe formed between 30 and 150 million years after the Big Bang and were massive behemoths, with masses up to 200 times that of our Sun. Scientists think those stellar first born burned brightly and quickly, lasting only a few hundred million years before exhausting their fuels and winking out as black holes or exploding as supernovas. HE 1523 "is probably a 0.8 solar mass star, and that's why it can still survive until today."

May 9, 07: The hottest planet ever discovered is charcoal black and makes even some stars seem cool. Scientists think the exoplanet absorbs nearly all the starlight that reaches its surface and then reradiates it back out into space as heat.
. . Called HD 149026b, the feverish world emits so much infrared heat that it glows slightly. "It would look like an ember in space, absorbing all incoming light but glowing a dull red", said study leader Joseph Harrington of the U of Central Florida.
. . HD 149026b is a so-called hot Jupiter, a giant gas planet that orbits very close to its star. It is a scorching 2,040 degrees C, three times hotter than Mercury and hotter than the coolest stars.
. . Until very recently, HD 149026b was also the densest planet known. It contains higher levels of heavy elements-those other than hydrogen and helium-than all of the planets in our solar system combined, and its core might have up to 90 times the mass of the Earth.
. . How HD 149026b got to be so hot is a mystery. "We've actually done a lot of work to try and answer that question, but the more we think about it, the worse it gets." One idea, proposed by Jonathan Fortney at NASA Ames Research Center in California, is that the planet is so hot that metals such as titanium and vanadium can exist in their gaseous forms in the planet's atmosphere. Such metals are "very, very, very strong visible [light] absorbers", said Fortney.

May 9, 07: The first-ever temperature map of a world outside our solar system confirms some extrasolar planets are heated by supersonic winds that ferry heat from their day sides to their night sides. The map has implications for a large class of giant gas planets that orbit very close to their suns, called "hot Jupiters."
. . HD 189733b orbits a star located 60 light-years away that is slightly cooler and less massive than Sol. It orbits its star at a distance of only 5 million km; one year on the planet is equal to only 2.2 Earth days.
. . Its a so-called "transiting" planet, meaning it passes directly in front of its star as seen from Earth. Like other hot Jupiters, its also tidally locked to its star, the way Luna is to Earth, so only one side of the planet is illuminated by its star. The supersonic winds can reach speeds of 9650 kph (6,000 mph)-nearly 8 times the speed of sound.
. . Using an infrared camera on board NASA's Spitzer Space Telescope, Heather Knutson of Harvard U and her team observed HD 189733b as it passed in front of its star, collecting more than a quarter million temp readings of the system over a period of 33 hours.
. . The hottest region on the planet is a single hot spot on the day side of the planet that is twice as big as the Great Red Spot on Jupiter and a scorching 926 degrees C.
. . The coldest region of the planet is about 1,200 degrees F. The 500-degree difference is relatively small for a hot Jupiter, leading the researchers to suspect the supersonic winds are redistributing the heat from the planet's day side to its night side.
. . It is still uncertain at this point whether global gales redistribute heat on all hot Jupiters. Another team, for example, recently found evidence that supersonic winds on one hot Jupiter are not strong enough to warm its night side, and so the world is scorching hot on one side and freezing cold on the other.

May 8, 07: Scientists have detected a stellar explosion that is the brightest and most energetic ever recorded, and which could be the first evidence of a new type of supernova fueled by an antimatter engine. The "SN 2006gy" explosion occurred in a galaxy 240 million light-years away, called NGC 1260, and was 100 times more energetic than typical supernovas.
. . It brightened slowly for 70 days, and at its peak emitted more than 50 billion Sols worth of light --shining 10 times brighter than its host galaxy-- before dimming slowly. Most supernovas reach peak brightness in days to a few weeks. "We may have witnessed a modern-day version of how the first generation of the most massive stars ended their lives", Filippenko said.
. . Most supernovas are the result of stars with 8 to 20 times the mass of our Sun collapsing under their own gravity. Astronomers think something different happened with SN 2006gy, whose star was much bigger --about 150 solar masses. Stars this massive are extremely rare: Scientists estimate there are only a dozen or so such stars in the Milky Way's stellar population of 400 billion.
. . Supermassive stars are thought to produce so much gamma-ray light at the end of their lives that some of the radiation is converted into matter and antimatter, mostly electrons and positrons. Antimatter particles have the same mass as ordinary matter but opposite atomic properties such as spin and charge. Gamma radiation is the energy that prevents the outer layers of a star from collapsing; once it starts disappearing, the star's outer layer falls inward, triggering a thermonuclear explosion that destroys the star.
. . The new findings suggest some of the first stars in the early universe, which were also very massive, went out in spectacular explosions like SN 2006gy, instead of bypassing the supernova stage and collapsing directly into black holes.
. . Eta Carinae, the most luminous star in our Milky Way, is located some 7,000 light-years away and seems poised to undergo its own explosion at any moment. "This could happen tomorrow or it could happen 1,000 years from now." Eta Carinae is an unstable star currently radiating about 5 million times more energy than our Sun and is undergoing eruptions on its surface that are similar to what scientists think happened on the star that produced SN 2006gy just before it blew. Despite its relatively close proximity to us, Eta Carinae's death is not likely to pose any significant threat to life on Earth.

May 8, 07: Derelict rocket stages that propelled four spacecraft toward the edges of the Solar System and beyond are likely carrying Earthly bacteria out into the galaxy.
. . The four 'STAR' upper rocket stages, also known as kick motors, are responsible for booting Voyager 1, Voyager 2 and Pioneer 10 to the solar system's fringes, as well as sending NASA's New Horizons spacecraft on a path to Pluto. The rocket stages are themselves on course to move beyond the Sun's influence into interstellar space.
. . Although their roles were vital to their respective missions, the upper stages were not lavished with the same attention as the spacecraft they parted company with. "The upper stages were not required to be sterilized." These bacteria would have been emplaced by the hands and breath of the engineers who built the upper stages.
. . But are they still alive? "Survival is more likely than any 'thriving'", said Mark Burchell of the U of Kent in the UK. Cold temperatures would likely plunge a microbe into a hibernation-like condition called a spore state.
. . Bacteria have been revived on Earth after millions of years of dormancy and experiments involving the exposure of bacteria and lichens to space have revealed just how tough these simple organisms are. So how long might a microbe last in space, clinging to a rocket? "There is still debate", Burchell said. "1,000 years? 100,000 years? We don't know."
. . Belts of radiation might have sterilized the bacteria when each upper stage reached Jupiter. The Pioneer 10 upper stage passed closest to the giant planet and endured many times the radiation level lethal for humans as it plunged through Jupiter's radiation belts. But perhaps some survived. "Some bacteria are quite a bit hardier than humans, so this probably wasn't enough to kill shielded bacteria on the inside of the upper stage."

May 6, 07: A massive exploding faraway star —-the brightest supernova astronomers have ever seen-— has scientists wondering if a similar celestial fireworks show may light up the sky much closer to Earth sometime soon.
. . The discovery, announced today by NASA, drew oohs and aahs for months from the handful of astronomers who peered through telescopes to see the fuzzy remnants of the spectacular explosion after it was first spotted last fall.
. . Using a variety of Earth and space telescopes, astronomers found a giant exploding star that they figure has shined about five times brighter than any of the hundreds of supernovae ever seen before.
. . Observations from the Chandra X-ray telescope helped show that it didn't become a black hole like other supernovae and skipped a stage of star death. Unlike other exploding stars, which peak at brightness for a couple of weeks at most, this supernova, peaked for 70 days, according to NASA. And it has been shining at levels brighter than other supernovae for several months.
. . And even at 240 million light years away, this star in a distant galaxy does suggest that a similar and relatively nearby star might blow in similar fashion any day now or 50,000 years from now, Smith said. It wouldn't threaten Earth, but it would be visible to people in the Southern Hemisphere.

May 4, 07: Astronomers have found the heavyweight champion of extrasolar planets in the form of an odd alien world slightly bigger than Jupiter, but more than eight times as massive.
. . Dubbed HAT-P-2b, the super-dense planet is the most massive known to transit across its parent star, but the weirdness doesn't stop there. Its oval orbit is so extreme that it first bakes the planet, and then cools it off during an annual trip that takes just more than five days.
. . The planet is a gas giant in orbit around the star HD 147506, which is about twice the size of Sol and burns a bit hotter, in a system 440 light-years from Earth. Astronomers have found about 230 extrasolar planets. Its year is five days and 15 hours. It's about 1.18 times brighter than Jupiter and 8.2 times as massive, w 14 times Earth's gravity at the visible cloud top surface. If the planet contained about 50% more mass, it could have fired up nuclear fusion and burn as a star for a short while. "It's much denser than a Jupiter-like planet; in fact, it is as dense as Earth even though it's mostly made of hydrogen."
. . During transits, researchers can determine the physical size of extrasolar planets by measuring how much they dim the light of their central star.
. . The planet's extremely elliptical orbit brings it within about 4.9 million km of its parent star on the inside, and swings out to a distance of about 15.4 million km. Astronomers believe that the odd eccentricity of the planet's orbit --all previous extrasolar worlds found via the transit method have circular orbits-- may be due to another, outer world whose gravitational pull disturbs the path of HAT-P-2b.

May 1, 07: Empires may rise and civilizations and ecosystems may crumble in the billions of years to come, but matter as we know it will endure, according to a new study eyeing the future of the universe.
. . The universe's ceaseless expansion, accelerated by the still-unseen and mysterious dark energy, will ultimately yield an environment in which matter nonetheless remains while radiation energy dwindles away, researchers said. The finding runs contrary to previous thinking that suggested matter would gradually decay into a radiation-heavy universe.
. . They used mathematical models to determine that in the far future, radiation --including heat, light and all other forms-- will vanish faster than it can be replenished through the decay of matter into component protons, neutrons and electrons. At the crux of the issue is dark energy, a hypothetical field or energy which permeates space and tends to accelerate the universe's expansion.
. . Previous theories suggested that radiation, not matter, would win out in the end because matter would decay into additional radiation over trillions of years.
. . Over the next 100 billion years, dark energy is expected to accelerate the most distant galaxies and stars in the universe beyond the speed of light, meaning that they will be invisible to future observers. Some objects once visible at half the universe's current age of about 13.7 billion years are already invisible from the farthest vantage points, and in about 10 trillion years, only the local cluster of galaxies, including our own Milky Way, will be visible, researchers said.
. . After just one trillion years, Krauss added, astronomers will no longer be able to observe the universe's expansion, constant microwave background, red shift of galaxies and other cosmic hallmarks. "Those are really all at the basis of our modern understanding of cosmology."

Apr 30, 07: There is a certain type of cosmic explosion that becomes, in a flash, the brightest thing in the universe, emitting for a few seconds as much radiation as a million galaxies. Don't bother looking for one in the sky, though, since most of the light is in the gamma-ray part of the spectrum, a realm we can't see.
. . Astronomers observe these colossal gamma-ray bursts with space-based telescopes, however. They generally agree that only the birth of a black hole could supply enough spark for one of these intense flashes, but there remains a great deal of uncertainty over what converts the newborn black hole's energy into the radiation that astronomers detect. Recent observations suggest that this "converter" is a high-powered magnetic beam, and not --as many theorists believe-- a high-speed jet of hot material.
. . This is just the latest debate over these exceptionally luminous objects called gamma ray bursts. Researchers previously argued whether GRBs come from inside or outside our galaxy, then whether they emerge from a dying star or two neutron stars merging.
. . The current consensus [No, I very much doubt they've reached that 100% agreement point! Then there would be no debate.] is that most GRBs are the death knell of a massive star in a faraway galaxy. After exhausting its fuel supply, the star's core collapses into a black hole (or a comparatively dense neutron star), which acts as a "central engine" for two jets spouting out of the poles. These jets are where the energy of the collapse is transformed into gamma rays, but we only observe a GRB if we happen to be lined up with the barrel of one of the jets.
. . This overall picture is fairly well-established, but the big question, according to Tsvi Piran of the Hebrew U in Jerusalem, is what makes up the jets. But the Swift satellite, NASA's dedicated GRB observatory, has detected a number of GRBs that appear to defy the fireball model.
. . "What we find is that the central engine is not dying immediately but continues to inject energy into the flow for thousands of seconds", said theorist Dimitrios Giannios of the Max Planck Institute for Astrophysics in Garching, Germany. "This long activity is more consistent with magnetic models."
. . A star's magnetic fields is compressed and amplified when the star collapses to a black hole or a highly magnetized neutron star, called a magnetar. Models predict that the fields are strongest --roughly a million billion times that of Earth's magnetic field-- along the rotational axis, where they spiral out like an ever-widening corkscrew, according to Giannios.
. . Since magnetic fields have no mass, they are much easier to accelerate than matter. The fields would therefore be more efficient at carrying energy out of the central engine. Outward-moving magnetic fields would eventually dissipate their energy into gamma rays --most likely in a process similar to what happens in solar flares.

Apr 24, 07: An Earth-like planet spotted outside our solar system is the first found that could support liquid water and harbor life, scientists announced today. The newfound planet is located at the "Goldilocks" distance --not too close and not too far from its star to keep water on its surface from freezing or vaporizing away.
. . And while astronomers are not yet able to look for signs of biology on the planet, the discovery is a milestone in planet detection and the search for extraterrestrial life, one with the potential to profoundly change our outlook on the universe.
. . The new planet is about 50% bigger than Earth and about five times more massive. [in this case, I deduce that "bigger" means diameter.] The new "super-Earth" is called Gliese 581 C, after its star, Gliese 581, a diminutive red dwarf star located 20.5 light-years away that is about one-third as massive as Sol. It's one of the 100 closest stars to Earth. Red dwarfs are low-energy, tiny stars that give off dim red light and last far longer than stars like our sun. [Hmm... Life wuda had plenty of time to start & develop!] It's so dim, you can't see it without a telescope. It's low in the southeastern sky during the midevening in the Northern Hemisphere.
. . Gliese 581 C is the smallest extrasolar planet, or "exoplanet", discovered to date. It is located about 15 times closer to its star than Earth is to the Sun; one year on the planet is equal to 13 Earth days. Because red dwarfs, also known as M dwarfs, are about 50 times dimmer than the Sun and much cooler, their planets can orbit much closer to them while still remaining within their habitable zones.
. . It could be a very important target for future space missions dedicated to the search for extraterrestrial life. "On the treasure map of the universe, one would be tempted to mark this planet with an X", Delfosse said.
. . Two other planets are known to inhabit the red dwarf system. One is a 15 Earth-mass "hot-Jupiter" gas planet discovered by the same team two years ago, which orbits even closer to its star. Another is an 8 Earth-mass planet discovered at the same time as Gliese 581 C, but which lies outside its star's habitable zone.
. . Computer models predict Gliese 581 C is either a rocky planet like Earth or a waterworld covered entirely by oceans. "We have estimated that the mean temperature of this super-Earth lies between 0 and 40 C, and water would thus be liquid", Udry said.
. . David Latham, another astronomer at Harvard-Smithsonian CfA, echoed other scientists' praise of the discovery but said the next step is to find a similar world where the orbit of the habitable planet carries it between Earth and its parent star. This will allow scientists to observe it using the transit technique, whereby the small dimming starlight caused by the planet's passage across the face of its sun can be used to calculate its size. Only then can scientists determine for certain whether the world is rocky or covered by water, Latham said.
. . Seth Shostak, a senior astronomer at the SETI institute, said the Gliese 581 system has in fact been looked at twice before for signs of intelligent life. The first time was in 1995 using the Parks Radio Telescope in Australia; the second time occured in 1997 using the Greenbank Radio Telescope in West Virgina. Both times revealed nothing.
. . "It has been looked at twice, but that doesn't mean we shouldn't look at it again", Shostak said. "And indeed we should." Shostak said the Gliese 581 system will likely be looked at again over much wider range of the radio spectrum when the new Allen Telescope Array begins operations this summer.
. . Until a few years ago, astronomers didn't consider these stars as possible hosts of planets that might sustain life. About 80% of the stars near Earth are red dwarfs.
. . Based on theory, 581 c should have an atmosphere, but what's in it is still a mystery and if it's too thick, that could make the planet's surface temp too hot. Until now, all 220 planets astronomers have found outside our solar system have had the "Goldilocks problem."
. . Eventually, astronomers will rack up discoveries of dozens, maybe even hundreds of planets considered habitable, the astronomers said. But this one —-simply called "c" by its discoverers-— will go down in cosmic history as No. 1.
. . Gravity is 1.6 times as strong as Earth's so a 150-pound person would feel like 240 pounds. But oh, the view. The planet is 14 times closer to the star it orbits. Udry figures the red dwarf star would hang in the sky at a size 20 times larger than our moon. And it's likely, but still not known, that the planet doesn't rotate, so one side would always be sunlit and the other dark.
. . Distance is another problem. "We don't know how to get to those places in a human lifetime", Maran said. [even a probe would require an ion engine more powerful than any today. Even after a probe got there, it would take another 20.5 years for a data-beam to traverse the gulf back to Earth.]
. . Mayor predicted that NASA's Terrestrial Planet Finder and the European Space Agency's Darwin satellite would make increasingly significant contributions in the search for extraterrestrial intelligence. He said these institutions will be able to directly look for "signatures of life" on other planets, similar to the high presence of oxygen in our atmosphere, within 15 to 20 years.
. . Future missions, perhaps in 20 to 30 years, may be able to block the light from the star and take a spectrographic image of the planets. The color of the light coming from the planet can give hints of whether water, or perhaps large amounts of plant life, exist there.

Apr 20, 07: Astronomers have spotted a giant cloud of superheated gas 6 million light years wide that might be generated by a cluster of supermassive black holes.
. . The plasma cloud might be the source of mysterious cosmic rays that permeate our universe. "One of the most exciting aspects of the discovery is the new questions it poses", said study leader Philipp Kronberg of Los Alamos National Laboratories in New Mexico. "For example, what kind of mechanism could create a cloud of such enormous dimensions that does not coincide with any single galaxy or galaxy cluster? Is that same mechanism connected to the mysterious source of ultra high energy cosmic rays that come from beyond our galaxy?"
. . The plasma cloud is located about 300 million light years away and is spread across a vast region of space known to contain several galaxies with supermassive black holes, or active galactic nuclei (AGN), embedded at their centers. The cloud might be evidence that AGNs convert and transfer their enormous gravitational prowess, by a yet-unknown process, into magnetic fields and cosmic rays that spread across the universe.
. . The new finding could also help explain the unwanted and confusing "noise" scientists observe in the Cosmic Microwave Background (CMB), Kronberg said. The CMB is a ubiquitous radiation in the universe that is said to be a remnant of the Big Bang.

Apr 20, 07: A class of "failed" star called a brown dwarf emits beams of radiation that are thousands of times brighter than any released by Sol. They behave like an altogether different and exotic cosmic object called a pulsar. Brown dwarfs are stellar also-rans which lack the necessary mass to kick-start nuclear fusion reactions in their cores.
. . A bright flash from the brown dwarf was observed roughly every two hours. This radio emission requires these brown dwarfs to possess magnetic fields as powerful as those detected at the most magnetically active stars.
. . The periodic pulses detected from brown dwarfs are very similar to those observed from pulsars. But the whole system is on a much slower and smaller scale, so it is easier for astronomers to decipher what is going on. "It looks like brown dwarfs are the missing step between the radio emissions we see generated at Jupiter and those we observe from pulsars".

Apr 18, 07: Astronomers have determined how far away from its hot stellar neighbors a star must be if a swirling disk of dust around it is to stand a chance of forming planets.
. . Using NASA's Spitzer Space Telescope, scientists created the first maps of so-called planetary "danger-zones", areas where winds and radiation from super-hot stars can strip younger, cooler stars like our Sun of their planet-forming materials. The findings suggest that so long as cool stars lie beyond about 1.6 light years, or nearly 10 trillion miles, of any hot stars, they can form planets.
. . Previous studies found that the fragile protoplanetary disks can be destroyed by radiation from the most massive, hottest stars in the universe, called O-stars, in a process called photoevaporation. Ultraviolet radiation from an O-star heats and evaporates the dust and gas in the disk, while stellar winds blow the material away.
. . The scientists found that the closer the cool stars were to their O-stars, the less likely they were to have disks. Beyond 1.6 light-years of an O-star, about 45% of the stars had disks, while only 27% of those located within the danger zone of an O-star had disks.

Apr 18, 07: New technology developed to photograph faraway Earth-like planets actually works, NASA researchers now find. Most exoplanets seen until now are five to 4,000 times Earth's mass, and are either too hot, too cold or too much of a gas giant to be considered probable habitats for life.
. . Imaging Earth-like exoplanets is a daunting challenge because the dim starlight that such relatively small worlds reflect is easily overpowered by the glare of their far larger, brighter parent stars. Now two astrophysicists at NASA's Jet Propulsion Laboratory in Pasadena, Calif., have devised new techniques that can overcome this glare, enabling future space telescopes to snap pictures of Earth-like exoplanets up to 10 billion times fainter than the stars they orbit.
. . Two key obstacles all telescopes face when trying to image exoplanets are diffracted and scattered light. The system that senior research scientists John Trauger and Wesley Traub devised, dubbed the High Contrast Imaging Testbed, handles these hurdles with the aid of a blurry barcode and a flexible mirror.
. . The stellar coronagraph is made of two "masks" developed over the last five years. The first mask resembles a blurry barcode, and is centered on the image of the star the telescope is focused on. This specific collection of stripes diffracts the star's light, steering it off to the side toward the second mask, a hole leading to an opaque sheet that suppresses this glare. The light that passes through these masks comes from around the center of the telescope's point of view, "hopefully from any orbiting planets", Traub said.
. . "This is at least a thousand times better than anything demonstrated previously." The system "could literally be put on a space telescope today", Traub said. The researchers aim for it to go aboard the Terrestrial Planet Finder, which unfortunately has no launch date right now because of insufficient funding.

Apr 15, 07: Astronomers have speculated for years that dark matter could power certain unexplained sources of light in the cosmos. That interpretation has been controversial--not least because each of these unexplained sources would require a different set of dark particle properties. Now a pair of researchers has found a way to make the dark matter explanation more plausible. "It's an idea that actually unifies these things and can explain everything with one new particle", says astronomer Douglas Finkbeiner of the Harvard-Smithsonian Center for Astrophysics.

Apr 13, 07: The idea that other, less-massive, dimmer stars than the Sun could also host habitable worlds has long been debated. A particular class, M-Stars, are of interest simply because there are so many of them-they are the most common star in the galaxy. They're the cool stars that inhabit our neighborhood.
. . There's considerable interest in the question of whether M-Stars could host habitable planets. Would the planets be tidally locked with one face always directed toward the M-Star? Would flares wipe out life on the local planet? If M-Stars could host habitable planets, life may be much more widespread that we've previously thought. Thus, M-Stars are of interest to astrobiologists including SETI scientists who are searching for life beyond Earth.
. . Stars like Sol live (i.e., they fuse hydrogen into helium) for only about 10 billion years. No M dwarf that ever formed has yet to die; no M dwarf will die for more than another 100 billion years. With such long lifetimes, there are big possibilities for these small stars.

Apr 11, 07: If trees grow on other planets, their leaves might be red, orange or yellow, and not only in autumn, scientists say. Two new studies find that the color of a planet's photosynthetic organisms depend on the type of star the world orbits and the makeup of its atmosphere.
. . "You have a particular spectrum which is affected by the star's surface temperature, but once that light comes down through the atmosphere, the atmosphere filters that radiation," said study team member Victoria Meadows of the Virtual Planet Laboratory (VPL) at Caltech.
. . For example, our Sun radiates most of its energy in the green part of the visible spectrum. But ozone molecules in the Earth's atmosphere absorb much of this green light energy, allowing other colors, especially red, to filter through to the ground. The researchers want to figure out what those alternative biosignatures might be. It's unlikely, for example, that plants on alien worlds will be blue.

Apr 10, 07: Astronomers have detected water [vapor] in the atmosphere of a planet outside the Solar System for the first time. The discovery, announced today, means one of the most crucial elements for life as we know it can exist around planets orbiting other stars.
. . The finding confirms previous theories that say water vapor should be present in the atmospheres of nearly all the known extrasolar planets. Even hot Jupiters, gaseous planets that orbit closer to their stars than Mercury to Sol, are thought to have water.
. . HD209458b is a world well-known among planet hunters. In 1999, it became the first planet to be directly observed around a normal star outside our solar system and, a few years later, was the first exoplanet confirmed to have oxygen and carbon in its atmosphere. Itis separated from its star by only about 7 million km --about 100 times closer than Jupiter is to Sol-- and is so hot scientists think about it is losing about 10,000 tons of material every second as vented gas.
. . Barman took advantage of the fact that HD209458b is a so-called 'transiting planet', meaning it passes directly in front of its star as seen from Earth. It transits every three-and-a-half days. When this happens, water vapor in the planet's atmosphere causes the planet to appear slightly larger in the infrared part of the starlight than in the visible portion.

Apr 6, 07: Scientists have solved a decades-long mystery of a red glow that permeates our Milky Way Galaxy and other galaxies. The red glow is most prominent in a strange, dying star called the Red Rectangle, named for the bizarre structure that surrounds it.
. . The red light, astronomers now say, radiates from invisibly small clusters of dust that are now believed to glow because of newly described molecular forces that oppose each other on very small scales. The glow, called the Extended Red Emission (conveniently ERE for short) has been known but inexplicable for more than 30 years.
. . They employed some fancy theoretical chemistry calculations to the problem. The glow comes from unusual clusters of PAHs that are charged and highly reactive but, at the same time, "have a stable, closed-shell electron configuration as does any stable molecule on Earth", the researchers said. (PAHs: polycyclic aromatic hydrocarbons)
. . The research could help scientists better understand how soot is formed during combustion in diesel engines and jets, a process that's poorly understood. The PAHs might serve as seeds in a flame around which a soot particle forms, the scientists said.

Mar 30, 07: Astronomers using NASA's Spitzer Space Telescope have found that twin-star systems are just as likely to be surrounded by dusty debris disks as ones with only a single star. Debris disks are made up of mountain-sized rock chunks and other material that could be leftovers of planets that have formed in the system.
. . Astronomers have theorized that planets could form with little trouble in two-star systems, called binaries, despite the more complex gravitational tugging. The new study provides strong observational evidence to support that idea.
. . 40% of the binary systems they looked at had disks. This frequency is a bit higher than that for a comparable sample of single stars and suggests planets are at least as common around binary stars as they are around single stars. Surprisingly, most of the debris disks found in the new survey were around so-called tight binary systems, where the stars are separated by 500 AU or less.
. . Scientists know of about 50 planets that have two Suns, but all of them belong to 'wide' binary systems, where the stars are separated by about 1,000 AU.

Mar 22, 07: Astronomers just got their most detailed look yet at supersonic 'bullets' of gas piercing through dense clouds of hydrogen gas in the Orion Nebula. Each bullet is about ten times the size of Pluto's orbit around the Sun and travels through the clouds at up to 400 km per second --or about a thousand times faster than the speed of sound. [& a lil more'n 1/1000 the speed of light.]
. . The bulk of both the bullets and the surrounding gas cloud consists of molecular hydrogen. The tip of each bullet is packed with iron atoms that are heated by friction and glow bright blue in the new image. As the bullets plow through the clouds, they leave behind tubular orange wakes, each about a fifth of a light-year long.
. . The Orion bullets were first spotted in a visible-light image in 1983, and followed up by infrared observations in 1992. Astronomers think the enormous clumps of gas were ejected from deep within the nebula following some unknown violent event about a thousand years ago.

Mar 13, 07: A type of binary star system known to erupt in small frequent explosions every few weeks is now known to occasionally erupt in much bigger, cataclysmic blasts as well every 10,000 years or so. A shell of gas detected four years ago is left over from a large explosion.
. . Z Cam is a type of dwarf novas that currently experiences small explosions every three weeks or so. The new finding supports a 20-year-old theory-for which data never before existed-that double star systems can go through both large and small explosions rather than just one or the other.
. . Classical novas, another subclass of cataclysmic variables, erupt due to a sudden but large dump of material from the red dwarf onto the white dwarf. The explosions, therefore, occur less frequently but with such vigor that they are up to a million times brighter than dwarf novas. Classical novas leave behind larger shells of shocked gas.

Mar 12, 07: Black holes can't be seen, but astronomers identify them by their gravitational effects on surrounding material and by noting emissions of X-rays and other radiation from their maws.
. . Typically, a black hole is surrounded by a doughnut-shaped region, or torus, of gas. The view of the black hole's immediate surroundings is blocked by this torus by different amounts, depending on the orientation whether we're looking through it edge-on or looking down on the setup from above, the thinking goes. If true, then astronomers should find a range of absorption of the radiation from the nuclei of black holes-from nuclei that are heavily obscured and barely detectable to those that are not obscured at all, along with everything in between.
. . "Instead of finding a whole range, we found nearly all of the black holes are either naked or covered by a dense veil of gas", said Ryan Hickox of the Harvard-Smithsonian Center for Astrophysics. "Very few are in between, which makes us question how well we know the environment around these black holes." This study found more than 600 obscured and 700 unobscured.

Mar 12, 07: A galaxy assumed to have been a giant for the past 23 years is in fact a dwarf, according to new observations.
. . Because of its low density of stars and absence of other features, astronomers would normally classify such a galaxy as a dwarf elliptical --a small faint galaxy with little gas and dust that mainly consists of old stars. However, for years scientists thought that NGC 5011C was located in the more distant Centaurus cluster --located some 155 million light years away-- close to the NGC 5011B galaxy, its bright red companion. So they pinned it as a giant galaxy that was just far away.
. . Most galaxies are found in gravitationally joined binary pairs or in groups. So it was no surprise that the projection of NGC 5011C and NGC 5011B in the sky had astronomers believing that they were in the same cohort, at about the same distance from our own. But new data revealed that the two galaxies have very different red shifts.

Mar 8, 07: The explosive death of a massive star has broken the record for longest-lived light show. Observations from NASA's Swift satellite have revealed a so-called gamma-ray burst for which the afterglow remained visible for more than 125 days.
. . When a star that's 10 to 25 times as massive as the Sun checks out, it can release in a matter of seconds the same amount of energy that the sun will radiate over its 10-billion-year lifetime. Once ejected, these GRB jets slam into nearby interstellar gas, and the resulting collision generates an intense afterglow that can radiate brightly in X-rays and other wavelengths.
. . Swift's X-ray telescope monitored the afterglow until it faded out, a phenomenon that typically lasts for a week or two. But the afterglow from this burst started off so bright and faded so slowly that the telescope monitored it for months. The long-lasting light suggests an underlying engine that pumped energy continuously to the burst.
. . The central engine could be a magnetar, a neutron star with a mega magnetic field, the scientists suggest. The magnetic field puts the brakes on the magnetar's rotation. The energy from this spin-down could get converted into magnetic energy that flows into the initial blast wave that triggered the GRB in the first place.

Mar 6, 07: Black holes fling high-energy protons into space, where they zigzag around at near light-speeds before smashing into low-energy protons, finds a new study. The collisions send bursts of gamma rays flying out from the center of our galaxy, which explains for the first time the mechanism for the high-energy jets first spotted in 2004.
. . This proton-slinging could explain more than this cataclysmic light show deep in our galaxy. The scientists suggest other black holes in the universe could rely on the pinball mechanism to produce enormous jets of light.

Mar 1, 07: While looking at the galaxy cluster Abell 2667 with the Hubble Space Telescope, scientists found a spiral galaxy which they nicknamed the "Comet Galaxy." The gas and stars of the Comet Galaxy --moving through the cluster at speeds of more than 2 million mph-- are being stripped away by the tidal forces of the cluster. Also, the pressure of the cluster's scorching gas plasma --known as ram pressure stripping-- is adding to the damage.
. . "This unique galaxy, situated 3.2 billion light-years from Earth, has an extended stream of bright blue knots and diffuse wisps of young stars driven away by the tidal forces and the ram pressure stripping of the hot dense gas," said Jean-Paul Kneib, a study collaborator from the Laboratoire d'Astrophysique de Marseille.
. . Elliptical galaxies, scientists suspect, are transformation products of other types of galaxies, something no one has seen because the process takes billions of years. What they are observing now is some 200 million years into such a process.
. . The Comet Galaxy --with a little more mass than the Milky Way-- will eventually lose its battle against the tidal forces and pressures of the hot plasma acting on it and end up a gas-poor galaxy with a collection of old stars. "Millions of now homeless stars have been snatched away from their mother galaxy, which will lead the galaxy to age prematurely."

Feb 26, 07: The new South Pole Telescope (SPT) has successfully collected its first light as part of a long-term project to unravel one of the biggest mysteries in cosmology, researchers announced.
. . The goal of SPT is to learn the nature of mysterious dark energy, an antigravity force that permeates the cosmos and is driving the universe apart at an ever-increasing pace.
. . The telescope does not make conventional images. Instead, it will take advantage of excellent viewing conditions-cold and dry-in Antarctica to detect the cosmic microwave background (CMB) radiation. The CMB is said to be the afterglow of the Big Bang. On the electromagnetic spectrum, the CMB falls somewhere between heat radiation (infrared) and radio waves.
. . According to one idea, dark energy is Albert Einstein's cosmological constant: a steady force of nature operating at all times and in all places.
. . Another version of the dark energy theory, called quintessence, suggests a force that varies in time and space. Some scientists even suggest there is no dark energy at all, and that gravity merely breaks down on vast intergalactic scales.
. . To pinpoint when dark energy became important, SPT will use a phenomenon called the Sunyaev-Zeldovich effect, which distorts the CMB as it passes through the hot gas of intervening galaxy clusters. As the microwaves interact with gas in the clusters, some of the microwaves get kicked into a higher frequency. SPT will measure the slight temperature difference associated with the frequency change and produce an image of the gas in the cluster.

So far, scientists have found 213 planets outside the Solar System —-they are called exoplanets. But only eight or nine are in the right orbit and location for the type of study reported by three teams using NASA's Spitzer Space Telescope.
. . Winds blow somewhere between 500 and 2,000 mph.

Feb 21, 07: The most detailed analysis ever of light from the atmospheres of planets outside the Solar System has turned up no evidence of water but possible hints of clouds, scientists said. "What we found surprised us. Or more accurately, what we didn't find surprised us.'
. . Using NASA's infrared Spitzer space telescope, Charbonneau and team studied a so-called hot Jupiter planet. A year on HD 189733b is only 2.2 Earth days long and the planet is a broiling 1,700 degrees F.
. . The technology to tease apart the light from a distant planet and star is not available yet, so scientists use a different trick. 'Instead of separating the [light from the planet and star] in space, we separate them in time,' Charbonneau explained. 'We wait for the planet to pass out of view behind the star, and then we measure the brightness of the star very carefully. Then we gather data at any other time, when both the planet and star are in view. If you take their difference, then whatever's left over has got to be the light from the planet.'
. . Theory predicts that hot Jupiters contain large amounts of water vapor and also methane. To the researchers' great surprise, no signs of either of these two molecules were detected.
. . Results obtained by another team suggest the water and methane are present, but hidden by thick clouds. A team led by Jeremy Richardson of NASA's Goddard Space Flight Center also used Spitzer to obtain the spectrum of HD 209458b, another hot Jupiter located about 150 light years away.
. . The spectrum Richardson's team obtained also showed no signs of water or methane, but it did reveal hints of silicate-molecules containing silicon and oxygen. On Earth, silicates are a major component of rocks. On hot Jupiters, under scorching temperatures, silicates would exist as tiny dust grains that could coalesce to form clouds.
. . Looking for water will be one of the main goals of the Terrestrial Planet Finder. (TPF) would use an array of telescopes orbiting the Earth in formation to generate planetary pictures 100 times more detailed than those the Hubble Space Telescope could take.
. . TPF would use a developing technology called nulling to improve vision. Light waves from a star have crests and troughs, just like water waves. If the starlight from two separated telescopes comes together just right, the crests from one and the troughs from the other can cancel each other out, reducing or eliminating starlight.
. . TPF is targeted for launch in 2011, though it has not been funded. Before the mission can be designed, engineers still need to figure out how to control separate spacecraft flying in formation while also orbiting Earth.

Current black hole theory states that gravitational forces inside a black hole reach infinity. But this almost certainly can't be correct. The center of a black hole is known as the singularity. Theory predicts it is far smaller than an atom, yet contains all the mass and rotation of a star. Even for scientists who study black holes for a living, this idea is still mind-boggling. The theoretical rotation limit is 1,150 spins per second.

Feb 16, 06: A star found spinning more than a thousand times every second is thought to be the fastest rotating star known.
. . A neutron star is a burned out corpse that's collapsed into an incredible density rivaled only by black holes. It packs the mass of the Sun into a sphere the size of a city. It has been reduced to nothing but tightly huddled neutrons. A thimbleful would weigh a hundred million tons back here on Earth. The neutron star rotates rapidly because, like a skater pulling her arms in, all its momentum is now highly concentrated.
. . It is zipping around on its axis 1,122 times every second. That smashes the previous record of 760 spins per second for a neutron star.
. . There's a limit to how fast stars can spin. Too fast and they'd break apart. But since astronomers don't know the exact make-up of neutron stars, the speed limit is not known. "If we can find more stars that spin in this range, it will certainly allow us to exclude some models of their interior structure."
. . Sol, for comparison, spins on its axis once every 36 days as measured at its equator.

Feb 14, 07: The darkest galaxies in the universe, made nearly entirely of matter which researchers think can zip right through normal matter with virtually no effect, now might be explained by a new scientific model that sheds light on their strange existence. There are believed to be as many as 10,000 dark matter particles in any given cubic meter of space in the solar system.
. . Ethereal galaxies composed almost completely of dark matter are known to orbit the Milky Way and the nearby Andromeda galaxy. These ghostly galaxies, known as dwarf spheroidals, have been stripped of most luminous matter to become dark matter shadows that are almost devoid of gas and possess very few stars.
. . A typical dwarf galaxy might contain several billion stars, and the Milky Way 200 billion to 400 billion stars, a typical dwarf spheroidal might have fewer than a million stars. Dwarf spheroidals are thought to be plentiful thruout the universe, but they're so faint, only those nearby have been seen.
. . Kazantzidis and his colleagues have developed a scientific model that might explain their creation. The new model was tested via months of simulations of galaxy formation on a number of supercomputers around the world. It entails a combination of cosmic ultraviolet rays, an intergalactic version of wind resistance and gravitational tides.
. . The origin of dwarf spheroidals began roughly 10 billion years ago when the universe was still hot with ultraviolet radiation from primordial galaxies and massive stars, the model suggests.
. . Dwarf spheroidal progenitors began life as normal galaxies. Cosmic UV radiation heated their gases, making it easier to get stripped off. As the progenitor galaxies the researchers studied orbited the more massive Milky Way galaxy, they experienced ram pressure, or a sort of "wind resistance", from gas inside the Milky Way, he said. At the same time, the progenitor galaxies encountered the overwhelming gravitational forces from the Milky Way, which wrenched luminous stars away.
. . Over billions of years of orbits, nearly all the normal matter got stripped away from the progenitor galaxies, leaving behind dark matter that was not affected by either the cosmic ultraviolet radiation or the ram pressure, Kazantzidis said. What tidal shocking the dark matter did experience was not strong enough to pull away a substantial amount of it.
. . The research suggests many more small dark galaxies may surround massive galaxies like the Milky Way than are currently observed, potentially solving what is called "the missing satellites problem".

Feb 12, 07: A swarm of colliding comets is weaving a dusty death shroud for a distant stellar corpse and providing astronomers with rare proof that certain planetary system objects can outlive their suns. Using NASA's Spitzer space telescope, astronomers spotted a cloud of gas and dust surrounding a dead star, called a white dwarf, in the Helix nebula, located 700-light-years away.
. . "We were surprised to see so much dust around this star", said study team member Kate Su of the U of Arizona. "The dust must be coming from comets that survived the death of their sun."
. . Astronomers have long studied the white dwarf at the center of the Helix nebula, but dust had never been detected until now. Using Spitzer's infrared eyes, Su and her team spotted a dusty disk circling the dead star at a distance of about 35 to 150 AU.
. . When the star died, it first went through a red giant phase, swelling to a colossal size and engulfing its inner planets. Outer worlds, planetisimals and comets would have survived, but their once-neat orbits would have been thrown out of whack, putting some of them on collision courses with one another.
. . As part of its final death throes, the bloated, dying star expelled its outer layers, until only a small, dense and relatively cool core --the white dwarf-- remained. Meanwhile, the messy comet collisions occurring at the outer fringes of the system continued.

Feb 12, 07: Like milk, our Milky Way Galaxy and the rest of the universe is fortified with calcium, the stuff of strong bones [coincidentally, galaxo- means milk, specifically from the breasts of Hera!]. In fact, the cosmos contain 50% more calcium than previously thought, a new study suggests. Calcium is a soft metal and the fifth most abundant element in Earth's crust. Organisms depend on it.
. . Explosions of massive stars produce and eject lots of heavy elements into space. The building blocks of new stars, planets and life are released during the final moments of these supernova blasts.

Feb 12, 07: A new cosmic map confirms a close relationship between galaxies with supermassive black holes at their centers and the distribution of the invisible dark matter in the early universe. The new map reveals a close relationship between quasars and dark matter, as predicted from theory.
. . Although smaller than the Solar System, a single quasar can outshine an entire galaxy of a hundred billion stars. Compared to normal galaxies, quasars are extremely rare, about 200 million light years or more apart from one another on average. The new map was created using the Sloan Digital Sky Survey and includes more than 4,000 quasars, some as far as 11 billion light years away. The universe is estimated to be about 14 billion years old.
. . A major question in cosmology: How did the first quasars form at all? 'How did black holes grow to a billion times the mass of the sun when the universe was only a tenth of its current age?' Loeb said.

Feb 9, 07: A French satellite designed to hunt out new planets has started work after a series of successful tests, the European Space Agency said. Dubbed COROT, the satellite carries a telescope capable of detecting small, rocky planets by measuring the light emitted by a star and detecting the drop in brightness caused when a planet passes in front of it.
. . COROT will start scouring for planets after work to fine tune equipment is completed at the beginning of April.

Feb 8, 07: JWST's primary mirror will be 6.6m in diameter, compared with Hubble's 2.4m mirror. Hubble's primary mirror was made in one piece. JWST's primary mirror consists of 18 different elements, allowing it to be folded up into the rocket. Each of the hexagonal mirror segments measures 1.3m in diameter and weighs just 20kg. They are made of beryllium --one of the lightest of metals known to science. Although the completed primary mirror will be over 2.5 times larger than that of Hubble, it will weigh roughly half as much. Beryllium has been used in other space telescopes and has worked well at the super-frigid temperatures of space in which JWST will operate.

Feb 7, 07: The hunt for Earth-like worlds orbiting distant suns will get a big boost next year with the liftoff of NASA's Kepler mission. That spacecraft's job is to monitor 100,000 stars in a stellar staring contest intended to detect periodic decreases in a star's brightness --a falloff of light due to planets transiting their parent stars.
. . Kepler's pursuit of rocky Earth-sized planets is a step forward in taking on some tough but major questions, such as: Are terrestrial planets common or rare? What are their sizes and distances? What's more, how often are such worlds detected in the habitable zone --the region around a star where liquid water should be available on a planet, perhaps making it a homely place for life?
. . Kepler is a trailblazer for other innovative searches for terrestrial planets. Launch date for the $500 million Kepler mission is November 2008, to be lofted into a heliocentric, Earth trailing orbit by a Delta 2 booster. The spacecraft's operational life is four years, toting along enough life-sustaining expendables for six years.
. . Kepler is part digital camera on steroids and part light meter. It will appraise the brightness of stars every 15 minutes. Using precise photometry, the spacecraft can detect small decreases in stellar brightness as a planet transits its star. Three transits with a consistent period, brightness change, and duration would provide scientists the magic moment of proclaiming detection of an extrasolar planet.
. . The photometer will constantly gauge the brightness of 100,000 stars, searching for planets as they pass in front of their parent star. In seeing any brightness change, Kepler data can be used to determine the planet's size and orbital period.
. . Even if Kepler discovers that these planets are rare, it would provide valuable insight about the origin of our Earth. However, that notion doesn't sit well with Borucki. "If we don't find them we can't have Star Trek because they'll be nowhere to go."
. . The Kepler mission is a kind of spotter scope, an invaluable leg up for future planet searches, such as those projected for NASA's Space Interferometry Mission (SIM) and the Terrestrial Planet Finder (TPF)--although both projects appear to be in a never-never land of funding support at present.
. . Webster Cash is Director of the Center for Astrophysics and Space Astronomy at the University of Colorado. Cash has been working on an idea tagged as the New Worlds Observer, receiving early financial support and encouragement from the NASA Institute for Advanced Concepts (NIAC). New Worlds Observer "is a better way to solve the problem that the Terrestrial Planet Finder team has been struggling with", he suggested.
. . The proposal calls for two spacecraft --a large, self-propelled, flower-shaped starshade and a conventional-quality telescope positioned far apart in space. "The key thing is that the starshade stops light from the star from ever getting into the telescope", Cash said. "This is really what you want. This is the ideal goal for direct study of exoplanets."
. . The huge starshade --at least 30 meters from tip-to-tip-- is a space-based occulter that blocks light from a target star. "If luck is with you, you'll see a little cluster of tiny faint planets... an actual direct signal from the planets with no interference from the big bright star."
. . Viewed as a low-cost replacement for the Terrestrial Planet Finder, Cash said the New Worlds Observer starshade would have a price tag of some $500 million, optimized for use with about a 4 meter diameter telescope costing upwards of $1 billion. "We've got all the technology to do this today", Cash added. "If NASA were to fund it, we would be able to do this in seven years."
. . Cash has also sketched out a New Worlds Imager a much more complicated concept for the future. "It involves at least five spacecraft and has the goal of taking true images of the surfaces of exoplanets."

Jan 31, 07: A miniscule sensor could lead to a better understanding of the formation of new stars, planets, and the hole in the ozone layer by studying an obscure wavelength of radiation. The pinpoint-size detector, which senses the least explored region of the electromagnetic spectrum, to measure molecules and gases in planet's atmospheres. "The sensor is especially suited to detect molecules in interstellar gas clouds, but also to detect trace gases in atmospheres in planets, including our own."
. . The electromagnetic spectrum runs from long-wavelength radio at one end to high-energy, short-wavelength X-rays and gamma rays on the other. Between microwaves and X-rays, lie T-rays, or terahertz radiation. Terahertz radiation is the most common form of radiation in the universe, if not one of the least publicized. When heated, the detector, called a hot electron bolometer or HEB, becomes sensitive enough to obtain information on the terahertz signal.
. . The sensor's first mission is slated for 2008 --to study the hydroxyl radical and other molecules in the sky above Brazil, an important step toward understanding the thinning of the ozone layer.
. . Astronomers will also employ these detectors in the new HEAT observatory in Antarctica, for a detailed study of the interstellar matter of the Milky Way. They will also use the sensors to better understand the formation of new stars.
. . The Herschel Space Observatory, a satellite due to launch in 2008 is the terahertz version of the Hubble telescope. In Chile, one of the world's largest telescope arrays, the Atacama Large Millimeter Array (ALMA), is being constructed; it will monitor terahertz wavelengths in hopes of spotting objects in the very early universe.
. . Many everyday materials, such as clothing, plastics, and wood look transparent under terahertz imaging, so the technology can be used to spot concealed weapons.

Jan 31, 07: HD 209458b is so hot that its atmosphere appears to be puffed up. The Jupiter-size planet is just 7 million km from its star. With the Hubble Space Telescope, astronomers measured starlight that filtered through the planet's puffy outer atmosphere. Astronomers can calculate an atmosphere's structure and chemical make-up by studying how starlight filters through it.
. . "The layer we studied is actually a transition zone where the temperature skyrockets from about 1,000 degrees Kelvin to about 15,000 Kelvin, which is hotter than the Sun", Ballester said. "With this detection, we see the details of how a planet loses its atmosphere."
. . With such an intense heat source, the gas streams from the planet's gravitational pull at a rate of 10,000 tons a second. Observations revealed oxygen, carbon, and sodium in HD 209458b's atmosphere, as well as in its fan-like tail.

Jan 29, 07: Streams of glittering stellar gems on the outer edges of Andromeda are remnants of an ancient galactic collision that helped shape the spiral galaxy.
. . Astronomers using the DEIMOS spectrograph on the Keck II Telescope in Hawaii determined this by surveying Andromeda, our galaxy's nearest large galactic neighbor, and discovered a trail of stars which they believe were part of a different galaxy that merged with Andromeda some 700 million years ago. The strong gravitational forces of a large galaxy, Gilbert explained, can rip apart a small galaxy, producing loose streams of stars that astronomers call tidal debris.
. . This could help astronomers calculate Andromeda's total mass, a slippery value that, once arrived at, could help shed light on the elusive dark matter that pervades the universe.
. . The discovered tidal debris features are almost an exact match with the features predicted in the computer simulations, Gilbert said. This implies that this new stellar stream and the giant southern stream, as well as the other stellar features reproduced in the simulations, came from the same parent galaxy.
. . Gilbert's discovery of a new tidal debris feature, combined with velocity measurements of the other related tidal debris, will provide observations necessary to measure how much dark matter is in Andromeda, he said, and how it is distributed.

Jan 24, 07: The Webb Space Telescope will replace Hubble, probably after 2011, and should be able to catch phenomena which happened 13.5 billion light-years ago. At these distances, the instruments onboard will need to be more precise than ever. This is why NASA has developed a new technology based on microshutters for a better focus of distant galaxies. These arrays of microshutters, composed of more than 62,000 individual shutters measuring 100 by 200 microns, will allow scientists to systematically block out light that they do not want, allowing the large-format detector to measure infrared spectra optimally —-and to perform spectroscopy on up to 100 targets simultaneously.
. . NASA engineers and scientists have created something that will give better information about far away galaxies. This new creation, which will be in a future space telescope, is so tiny that it's the width of a few hairs. "Microshutters" are tiny doorways that bring stars and galaxies very far away into better focus.

Jan 16, 07: A recent sky survey has turned up eight new members in our Local Group of galaxies, including a new class of ultra-faint "hobbit" galaxies and what might be the smallest galaxy ever discovered. The new galaxies were detected over the past two years as part of the Sloan Digital Sky Survey (SDSS-II) and presented last week.
. . The Local Group is a collection of about 40 galaxies, of which the Milky Way and Andromeda are the dominant members. The rest of the galaxies are mostly small satellites known as "dwarf galaxies" that are gravitationally bound to these two galaxies. The Large and Small Magellanic Clouds are two of the Milky Way's better known dwarf galaxies.
. . Seven of the new galaxies are gravitationally bound to the Milky Way, while the eighth appears to float freely in space, beyond our galaxy's grasp. The new Local Group members are even smaller and fainter than other known dwarf galaxies, with luminosities ranging from only a thousand to at most a few hundred thousand times that of our Sun. "They seem to be much fainter than anyone suspected galaxies could be before." The dimness could be the result of stellar age, as seven of the new galaxies contain mostly old stars.
. . Current galaxy formation theories predict our Milky Way should be surrounded by a swarm of smaller satellite galaxies. But until the new survey, only twelve had been identified. Astronomers have dubbed this issue the "missing satellite problem."
. . The new galaxies could go a long way toward solving this problem and might represent just the tip of a cosmic iceberg, the researchers say. "The Sloan Digital Sky Survey covers only a fifth of the night sky, so there must be many more dwarfs out there."

Jan 13, 07: Distant objects in the Universe are moving away from us at very fast speeds - and this has an interesting effect on the light they emit. It gets shifted to longer wavelengths: the "red" part of the spectrum. The infrared is therefore essential to seeing the farthest --and therefore the earliest-- objects to form in the Universe, a consideration that was one of the most important driving factors behind the design of the telescope.
. . The James Webb Space Telescope, named after a former administrator of Nasa, is not going to repeat the science carried out by its predecessor. While Hubble gazed at the Universe in optical and ultra-violet wavelengths, JWST will look primarily in the infrared. Infrared wavelengths are also good for seeing through the cocoons of dust that often obscure stars and planets in the process of formation. But infrared light does not penetrate the Earth's atmosphere very well. This was one reason why an infrared telescope was needed in space
. . In addition, the telescope needs to be cold, otherwise it will emit its own infrared radiation, swamping faint astronomical signals. "It's designed to operate at cryogenic temperatures, on the order of 40 Kelvin. The large shield that visually dominates the spacecraft is designed to block light from the Sun, Earth and Moon that would otherwise heat up the telescope. For this to work, it cannot be put in low-Earth orbit like Hubble. It must be in an orbit where all three of these objects are in about the same direction. The most convenient place is "L2", one of five gravitational balance points in space, where it can stay fixed in the same spot relative to the Earth and the Sun.
. . JWST's primary mirror will be 6.6m (22ft) in diameter, compared with Hubble's 2.4m (7.9ft) mirror. "Hubble is a conventional telescope. It has a 2m primary mirror with a secondary mirror. JWST has a segmented primary mirror comprised of 18 individual elements", said Mark Clampin. "It gives us a lot more flexibility during its lifetime because we can actually tweak up the performance of the telescope.
. . The mission aims to examine every stage in cosmic history and the science priorities are organized into four main themes:
. . * the end of the cosmic "Dark Ages"
. . * the assembly of galaxies
. . * the birth of the first stars and protoplanetary systems
. . * planetary systems and the origin of life

JWST should also be able to detect extrasolar planets through the transit technique and examine the formation of planetary systems. "We may be able to see something about the atmospheric chemistry of planets. If the planet's small enough, we may be able to learn about organic chemistry on an Earth-like object", said John Mather.
. . The agency has been re-structured to pay for President Bush's Vision for Space Exploration --which involves returning humans to Luna by 2020-- science budgets have been slashed, resulting in many robotic missions being dropped.
. . The telescope is due to launch on a European Ariane 5 from Kourou in 2013. With its tennis court-sized sunshield and huge mirror, JWST is so big it has to be folded up to get it into the rocket fairing. The process of unfurling it in space is extremely complicated, and engineers are modelling this through computer simulations.

Jan 11, 07: A pioneering US space agency spacecraft is set to launch on a mission to explore the most energetic phenomena in the Universe. The Gamma-ray Large Area Space Telescope (Glast) has been described as an "extreme physics" laboratory.
. . Gamma rays are the most energetic form of radiation known to science. Examples of energetic phenomena to be probed by Glast include active galaxies (quasars). Other targets for Glast include pulsars --rotating neutron stars which emit radio waves-- as well as the remnants of exploded stars, and galaxy clusters.
. . Mission scientists hope to address several unanswered questions about the high energy Universe. One question central to the mission is where in the Universe cosmic rays are accelerated to tremendous energies. Cosmic rays are composed of atomic nuclei that can move at close to the speed of light. They can be about one billion times more energetic than the high energy particles created on Earth in the most powerful particle accelerators.

Jan 11, 07: Massive stars and their dead brethren are teaming up to build a colossal space bubble outside our Milky Way galaxy.
. . Expanding envelopes of gas and dust shed by massive stars and supernovas are in the act of merging in a peculiar region of the Small Magellanic Cloud, one of two dwarf galaxies near the Milky Way. "We are witnessing the birth of a superbubble", said Rosa Williams, an astronomer at the University of Illinois.
. . The cosmic formation not only gives astronomers a deeper glimpse into the lifecycles of massive stars, but may also prove fruitful for planetary formation research. During their lifecycles, massive stars generate --and ultimately distribute via supernova-- the heavy elements that are crucial for the formation of planets, researchers said.

Jan 10, 07: The neutron star inside the Crab Nebula may have as many as four magnetic poles, the American Astronomical Society meeting in Seattle has heard. If the findings were confirmed, the neutron star would be the first cosmic object found to have four poles.
. . The magnetic poles were essentially "frozen" into the remnant after the supernova explosion. The cosmic explosion may have been very asymmetric: "Any models you see of supernova explosions are incredibly convoluted. It just doesn't go down as sphere and rebound as a nice sphere. "The magnetic pole is frozen in so it gets all mixed up as well."

Jan 10, 07: A flurry of lint-like particles discovered swirling around a small, distant star could help explain how miniscule interstellar dust grains clump together to form planets, astronomers say. "We have seen many seeds of planets and we have seen many planets, but how they go from one to the other is a mystery", said study team member James Graham of the University of California, Berkeley. "These observations help us to fill in that gap."
. . The newfound fluffy particles are about ten times larger than interstellar dust grains and about as porous as newly fallen snow, which is composed of about 97% air and only 3% ice.
. . The space lint was detected in a disk encircling AU Microscopii, a relatively young red dwarf star, just 12 million years old, located 32 light-years from Earth. "Once they exceed softball sizes, they start to become compactified. The vacuum in between the grains get filled with more material."
. . Small crashing parent bodies are thought to shed the fluff, which is then blown outwards by the star's intense solar winds.

Jan 10, 07: Heated winds on at least three planets outside the Solar System blow so strongly that the worlds are kept at a constant toasty temperature, even on their night sides that never face their parent stars.
. . The planets are called "hot Jupiters" because they are large and gaseous like Jupiter, but orbit much closer to their stars. All three orbit within about eight million km of their stars, much closer than Mercury is to our Sun. Scientists think winds on the planets blow at supersonic speeds, as strong as 14,500 km per hour, churning their home worlds' atmospheres and keeping temperatures on their dark sides from plunging.
. . Hansen's team found that one half of Upsilon Andromeda b was as hot as molten lava, while the other half was chilled possibly below freezing (of water). The researchers speculated that the sunlit side of the fire and ice planet was perhaps tidally locked to its stellar parent, like Luna is with Earth.
. . In late 2005, the researchers used NASA's Spitzer Space Telescope to gather infrared readings from each of the planets at eight different positions in their orbits. They measured the thermal brightness of the planets when their day sides faced Earth, when their night sides faced Earth and at various phases in between. They found no variation in the infrared brightness, suggesting no widely varying temperature differences between the planets' day and night sides. Instead, the planets all appeared to have a uniform temperature of about 925 degrees C.
. . "There has been some speculation that life might be able to exist on the cooler night-side of hot extrasolar rocky planets, but if those planets had similar weather patterns in their atmospheres as these hot Jupiters, that may not be the case."

Jan 10, 07: A new detailed study that tracked two of the Milky Way's galactic neighbors, the Large and Small Magellanic Clouds, shows they are hurtling through space nearly two times faster than previously thought. The two clouds, which are actually miniature galaxies, have long been thought to be gravitational companions to our own much larger galaxy. The finding raises a number of surprising possibilities, any of which-if borne out-could rewrite astronomy textbooks.
. . One explanation is that the Milky Way is twice as massive as previously thought. If the star-packed clouds are gravitationally bound to our galaxy as commonly thought, then the Milky Way must be more massive to maintain its grip on such fast-moving objects.
. . Another possibility is that the clouds are not bound to our galaxy, but merely visiting passersby that will escape the Milky Way in a few billion years.
. . Yet another alternative is that the dark matter distribution of the Milky Way is not pancake-shaped or spherical as some theories have predicted, but that it is strewn in some other way that allows our galaxy to keep a firm gravitational grip on the clouds.
. . The researchers took two measurements, spaced two years apart, and found that the Large Magellanic Cloud is speeding through space at about 378 km per second relative to the Milky Way, while the Small Magellanic Cloud is moving at about 302 kps --about twice as fast as previously thought. The relative velocities of the clouds to each other is about 100 km per second, fast enough for them to break apart.

Jan 8, 07: Long baffled by their origin, scientists now have evidence that charcoal-colored black diamonds formed in outer space.
. . Stephen Haggerty and Jozsef Garai, both of Florida International U, analyzed the hydrogen in black diamond samples using infrared-detection instruments at the Brookhaven National Laboratory and found that the quantity indicated that the mineral formed in a supernova explosion.
. . Also called carbonado diamonds, meaning “burned” or “carbonized” in Portuguese, black diamonds defy mineral-making rules and are never found in the world’s mining fields, where the clear and classic variety typically resides.
. . Conventional diamonds form hundreds of miles beneath the Earth’s surface, where high pressure and heat turn carbon into diamonds. Volcanic blasts send the gems in a short amount of time to the surface where they can be mined. Since 1900, about 600 tons of conventional diamonds have been traded. Black diamonds reside in certain geologic formations in Brazil and the Central African Republic.

Jan 8, 07: The discovery of three distant supermassive black holes in close proximity to each other is giving astronomers a glimpse into the chaotic early years of the universe.
. . Known as quasars, these incredibly bright objects are thought to be powered by gas falling into enormous black holes situated in the centers of galaxies. Although smaller than our solar system, a single quasar can outshine an entire galaxy of a hundred billion stars.
. . Roughly 100,000 quasars have been observed in recent years, some of them double quasars. But this is the first time that three quasars have been found so near one another. The three quasars are separated by about 100,000 to 150,000 light years --about the width of our Milky Way.
. . Rasio's work also predicts that triple quasar encounters could eject one or more of the bright objects straight out of the host galaxy. These "naked" quasars are then destined to wander alone through the universe.

Sept 26, 03: [Yes, '03. just came across it.] Thousands of stars stripped from a nearby dwarf galaxy are streaming through our own Milky Way, according to astronomers. These "alien" stars could at times be close to our Sun, they say. The interlopers were spotted on a new survey of the entire sky.
. . The analysis is the first to map the full extent of the nearby Sagittarius galaxy, showing how this galaxy, which is 10,000 times smaller in mass than our own, is being stretched out - torn apart and devoured by our Milky Way. They digitally removed millions of foreground stars to leave a type of star called an M giant. These large, infrared-bright stars act as tracers because they are populous in the Sagittarius galaxy but uncommon in the outer Milky Way.
. . The new image shows that stars and star clusters now in the outer parts of our Milky Way have been ripped from Sagittarius by our Milky Way's gravity. "We are seeing Sagittarius at the very end of its life as an intact system."
. . Majewski and his colleagues have been surprised by the Earth's proximity to a portion of the Sagittarius debris. "For only a few percent of its 240-million-year orbit around the Milky Way galaxy does [the] Solar System pass through the path of Sagittarius debris", Majewski says. "Remarkably, stars from Sagittarius are now raining down on to our present position in the Milky Way. "Stars from an alien galaxy are relatively near us. We have to re-think our assumptions about the Milky Way galaxy to account for this contamination."

Jan 8, 07: Astronomers have found an enormous halo of stars around the Andromeda galaxy. The discovery suggests the nearby spiral galaxy, also known as M31, is as much as five times bigger than astronomers had previously thought. In fact, Andromeda's "suburbs" are so vast that they nearly overlap with those of our own Milky Way galaxy.
. . Andromeda is a spiral galaxy similar to the Milky Way. About 2.5 million light-years away from Earth, it is the largest galaxy in the "local group", which also includes the Milky Way and about 30 smaller galaxies.
. . The halos of distant galaxies are nearly impossible to resolve, because astronomers cannot see individual stars. Andromeda is at the perfect distance: it is just far enough for astronomers to see the whole galaxy, and just close enough for them to observe individual stars. They detected a sparse population of red giant stars --bright, bloated stars in a late stage of stellar evolution. These appeared to be smoothly distributed around Andromeda out to a distance of 500,000 light-years from the galaxy's center.
. . They developed a technique that allowed true Andromeda stars to be isolated from other objects along the same line of sight. They found a clear break in the surface brightness of stars from the inner parts of Andromeda and fainter ones from outer parts of the galaxy.

Jan 8, 07: Astronomers have mapped the positions of vast, invisible isles of dark matter in the sky, within which normal "bright" matter galaxies are embedded like glittering gems. The three-dimensional map spans not only space, but also time, and stretches back to when the universe was only about half its present age.
. . Even though dark matter can't be seen directly, some scientists say its presence and distribution in the universe can be observed indirectly by the way its gravity distorts the light of distant galaxies streaming toward us.

Jan 7, 07: Astronomers have found evidence of a massive black hole at the heart of a dwarf elliptical galaxy. The galaxy is just 1% the mass of our own Milky Way, and its black hole is estimated to be somewhere between 1 million to 50 million times the mass of our Sun. That's a lightweight compared to some supermassive black holes --which can be billions of times as massive as a star-- but considerably more hefty than stellar black holes, which weigh only as much as a few suns.

By analyzing the distortions in galaxy shapes, they inferred properties of the dark matter "lens" itself, including its mass and position in the sky. This confirms what previous, smaller, maps have hinted at: Dark matter is distributed across the universe in thick clumps and fat filaments within which galaxies are anchored.
. . The map relied on data collected from more than half a million galaxies and spans a swath of the night sky that is nearly nine times the diameter of the full Moon. "We've seen the first glimpse of the cosmic web which acts as the basic framework for large scale structures."
. . The new map reveals that as time passed, from the early universe to the more recent universe, dark matter became clumpier and less filamentary. "It collapsed first into these filaments and clusters and provided the gravitational scaffolding into which normal matter-galaxies, planets, us-flowed", Massey said. "It's only because there's a lot of dark matter and it collapsed first that we can exist at all."
. . Some skeptics think there is a good reason dark matter is invisible: It doesn't exist. According to these scientists, an alternative explanation for the universe's mass discrepancy is that gravity does not operate equally in all parts of the universe, as is predicted by Newton and Einstein.
. . Zhao is an advocate of a theory of modified gravity called TeVeS, in which gravity is stronger in certain regions of space than others. In these gravity-boosted regions, gravitational lensing would work differently.

Jan 8, 07: Astronomers plan to search 1,000 nearby stars for television broadcasts and other signals that could indicate extraterrestrial life, the Harvard-Smithsonian Center for Astrophysics said. The project, planned for early 2008, would use a new radio telescope to search for radio traffic similar to that found on Earth.

Jan 3, 07: With a big enough radio telescope, astronomers could create a map detailing the structure and distribution of invisible dark matter in the universe up to 10 times sharper than previous ones made using visible light telescopes.
. . Streaming light from distant stars and galaxies is bent slightly by the gravitational effects of large foregrounds objects --such as other stars, galaxies, or large dark matter clumps-- that they travel past. The bending causes a detectable distortion of the images of the distant objects similar to the distortion observed in the reflections of rippled water in a lake. By measuring the strength of the distortion, scientists can calculate the strength of the gravity and mass of the foreground objects. Using this technique, called gravitational lensing, scientists have created density maps of large objects in the universe, including clumps of dark matter.
. . Previous maps created using optical telescopes suffer from blurriness, however, because many distant light sources are required to make a sharp image, and there are not enough visible galaxies in the sky for this. Only the very largest lumps of matter, corresponding to the very biggest galaxy clusters, can be pinpointed with any confidence on such maps.
. . Another problem is that many of the massive objects, such as primordial hydrogen clouds present before the first stars or galaxies ever formed, lie behind the galaxies whose visible light scientists are measuring. As a result, the more ancient structures in the universe are invisible to many of today's instruments. To view these objects, scientists need many more distant light sources. Radio waves could provide these sources.
. . More ancient than visible light are radio waves, some of which can be traced back to a time before galaxies. There are also many more radio wave sources in the universe.
. . About 400,000 years after the Big Bang, hydrogen and helium atoms permeated the universe. Over the course of a few hundred million years, gravity caused these gases to clump together to form dense clouds. Eventually, these clouds coalesced into the first stars and galaxies whose radiance put an end to the universe's "dark age."
. . Theory predicts that ultraviolet light from these early celestial bodies heated the hydrogen and helium and caused the hydrogen atoms to emit and absorb radio waves of a specific wavelength: 21 cm. As the universe expanded, this wavelength expanded as well, and today should be about 2 to 20 meters long. You need something like 100 km.
. . No radio telescope that big is currently planned, but a smaller project, called the Low Frequency Array, or LOFAR, being constructed in the Netherlands and Germany, could provide similar, albeit lower resolution, radio pictures of the sky. LOFAR's arrays will be arranged in clusters and scattered over an area about 350 km (217 miles) in diameter. However, its most sensitive core array --the part required to do the type of imaging the researchers propose-- will only be about 7 km across.

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