Astronomy

A practicing astronomer intercepts signals such as radio waves, light waves, and gamma rays, which all travel at the same speed, approximately 186,000 miles per second. This speed provides a natural standard for gauging distance. The interval between transmission and reception of a signal, multiplied by the speed above, converts to distance. The light year converts to nearly 6 trillion miles. This unit neatly unifies space and time. The distance that objects are seen not at it is now but as it was then.

If the Universe were truly static and unchanging, time itself would be frozen.
It is only in this process of change that we comprehend the concept of time.

Just think it takes that long for the light to hit our eyes, pass through the retina, which changes the image, then changes to a chemical impulse that reaches the brain. The electrical impulse of light is therefore absorbed into the body. This is one way we are part of the Universe.

	The Milky Way Galaxy The stars of our own galaxy are not scattered randomly through space. The brightest and the youngest stars are located within the plane or disk of the galaxy. These arms when viewed face on, give the appearance of a saucer shape The astronomy satellite, IRAS, took the infamous pictures showing a cross section of our entire galaxy. We are in fact located in just one arm of this enormous spiral of dust and gas. The entire flattened disk with the nucleus at the center, is 100,000 light years across. Within this disk there are hundreds of billions of stars. From the nucleus, these great arms spiral out that look like rivers of stars. Unfortunately we cannot yet see into the center of our galaxy due to obscuring dust clouds. Perhaps one day we will have the technology to do so. Amazingly the whole galaxy rotates as one object.
"When we try to pick out anything by itself we find it hitched to everything else in the universe." John Muir.
	The Andromeda Galaxy Andromeda is the closest galaxy to our own. This neighbor is about 2.3 million light years away. Its spiral structure mirrors that of the Milky Way but is considerably larger. It is 150,000 light years across and contains many more stars.It is the farthest object we can see without a telescope. The naked eye can pick out a faint fuzzy object in the night sky if you know where to look. The distinctive oval can be seen with binoculars and with telescopes you can see individual stars and a dark dust lane. There are also two companion galaxies that can be seen with binoculars that are close in proximity to the Andromeda Galaxy. These Galaxies can be found in the Andromeda Constellation near Cassiopeia. Cassiopeia is the one that looks like a giant relaxed W or M in the sky.
	Black Holes There are stars that tolerate no resistance to collapse. Atomic and nuclear pressures are so great that these huge masses crush themselves out of existence. It disappears from sight when the gravitational fields become so intense that light cannot escape. "Black" describes a void or absence of light, and holes are rips in the fabric of space. Their densities would mean that a teaspoon of black hole matter would weigh as much as Earth itself. The density is derived from mathematical calculations that won't be covered here due to the complexity of the subject matter. See Science links. No signals can break this tremendous barrier. Both time and space are warped near the neighborhood of the hole. Speeds increase to the unimaginable and density rises to an incomprehensible level. Light is emitted from the space matter that is hurling towards the vortex and can be seen as x-ray emissions. We can not see the black hole itself, due to no light given off, but we can detect their presence by the effects of the surrounding matter.

Anatomy of the Stars

The recent pictures of the Nebula in Orion where it is deemed the "nursery of the stars" show that stars are initially born within these billowing clouds of dust and gas formations. The friction and heat exchange changes the molecules. When a particular dense part of a nebula begins to shrink under the influence of gravity the atomic alliances make the molecules larger and larger thus forming rays of energy, starlight.

The star goes through different stages of development as it matures. The stages in order of growth are the yellow dwarf, blue-white, red giant, larger giant and the super giant. Our own sun is but an infant and is classed as a yellow dwarf. In about 5,000 million years hence, it will swell into a giant. Bigger stars expand into super giants that have diameters of many hundreds of millions of miles.

When the giant star blasts itself apart in the throes of death, the star supernovas. The outcome of the explosion depends on the original mass of the star. Some stars that have a mass up to about seven times the mass of our sun leave behind a dense neutron star which is about 12 to 20 miles (20-30 kms) across. Stars that have a great mass leave behind an enormous gravity of nothing, a Black Hole.

The chemically diverse atoms are propelled back into space, which in turn meets up with other molecules and the whole process begins again. The stars life cycle is "from dust to dust."

Radio telescopes can look into the dark and dusty regions of space to reveal all of the molecular elements that are out there. The emissions found through space vary from the simple formaldehyde to the most complex cyano-octatetrane, which consists of 11 atoms. Most of the molecules detected have the element of organic carbon. The very essence of our human body is made of carbon. The iron in our blood, the calcium in our bones and the water throughout our bodies, even the fillings in our teeth are sprinkling of stardust that exist only as lost galactic memories of long ago. What we are made of is scattered throughout space.

 

Can we assume that we are direct ancestors of some giant stellar explosion that started and ended as free-floating matter in space?

Maybe this would cause us to consider the possibility that life could arise elsewhere in the unfathomable depths of the Universe.

It would be arrogant to say that we could be the only ones. The possibility of other life equals the profundity of the possibility that we are the only ones.

Here are some numbers to ponder:

# of stars in our galaxy *300,000,000,000 (300 Billion)
# of planetary systems in our galaxy *280 billion
# of planetary systems in our galaxy that circle sun-like stars *75 billion
# of sun-like stars in our galaxy with a useful ecosphere *52 billion
# of habitable planets in our galaxy that contain a habitable ecosphere *650 million or 1 in 460
# of life-bearing planets in our galaxy *600 million
# of planets that have of cell bearing, multicellular life *433 million
# of planets that have rich land life *416 million
# of planets that have developed some technological civilization *390 million or 1 in 770

Now that is something to really think about!

(Taken from "Extraterrestrial Civilizations" by Isaac Asimov. The numbers are based on the premise of what scientists know of our life, earth and solar system. The book is based on the probability from what we already know to be.)

"For a moment of night we have a glimpse of ourselves and our our world islanded by its streams of stars....voyaging between horizons across the eternal seas of space and time." Henry Beston "The Outermost House"