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Timescales in open, flat, and very large closed universes

   This timeline of the future of our Earth, sun, and universe was derived mostly from a variety of sources on the web, as well as a few print publications.  I list the sources below (footnotes in years column).  This is largely an updated and much more complete version of the timeline found here.  That page also had a table listing information relating to a Big Crunch.  I have not included that table here, in light of recent discoveries and growing consensus that we live in an open universe.  In fact, some of the later dates may come to change significantly if evidence of a long-range gravitational repulsive force holds up.
   Some of these events preclude others; e.g. if protons decay around 1017 years, there will be no Hawking decay of matter later.  As with all predictions, those events closer to the present can be considered to be known with greater reliability.  However that is not strictly true here, since this timeline is a conglomeration of events derived using different methodologies and different levels of knowledge.  Nevertheless I consider it to be a scientifically accurate indicator of Things to Come.
   A brief reminder:  1 million = 106 = 1,000,000.  1 billion = 109 = 1,000,000,000.  1 trillion = 1012 = 1,000,000,000,000 = 1 million million.  (The U.S. federal debt is around $5.5 trillion!!!)
   I'm looking for info on how long it will take a terrestrial planet to lose its atmosphere, or if gas giants will eventually evaporate (diffuse) away.  Anyone know?
   The first few events are astronomy-related.  I hope you enjoy reading this.
Future Time
(years after
A.D. 2000)
Tentative Event
10,000 years18
Our sun exits the local interstellar cloud it is currently passing through.  (See diagram at reference #18 webpage, below.)
12,900 years1
Earth's axis has precessed 180, giving us a whole new North Star.
27,700 years
The southern hemisphere binary Alpha Centauri, or Rigel Kentaurus (now 4.35 light-years distant, with an apparent magnitude of -0.29), will reach a minimum distance from Earth of 2.84 light-years and should then be the second brightest 'star', with an apparent magnitude of -1.2.
59,000 years
Sirius A (Alpha Canis Majoris, aka the Dog Star), has an apparent magnitude of -1.46 but because of the relative motions of this star and the Sun then this should rise to a maximum value of -1.67.  Sirius is now 8.64 light-years distant and has a luminosity 26 times greater than that of the Sun.
100,000 years10
The Orion Nebula complex, including the Horsehead nebula, disperses away.
300,000 years15
Long-dead spacecraft Pioneer 10 passes within 3 LY of Ross 248, 10.3 LY away.
1-1.4 million years16,17
Gliese 710, a red dwarf star currently 63 LY away, swings in to within 62,0009,000 AU (<1 LY) of our sun.  No danger to us, except for some dislodged Oort Cloud objects.
1,250,000 years2
Delta (d) Scuti, prototype of a whole class of rapidly pulsating variable stars, takes the helm as the brightest "star" in the northern sky.
1,550,000 years2
Gamma (g) Draconis, aka the orange giant Eltanin star (the presently 2nd-magnitude nose of the constellation Draco), becomes the sky's brightest star, as bright as today's Sirius.
1.7-2 million years15
Pioneer 10, if still intact, passes near Aldebaran, 71 LY distant.
3,500,000 years2
Omicron (o) Herculis becomes the brightest star when it swings in from 350 to about 45 light-years from our sun.
4,600,000 years2
Beta (b) Cygni, aka Albireo or the beak of Cygnus, takes the brightest-star title.  Depending on whether it's a true binary and its orientation to us, it could appear to the naked eye as a tightly-bound 2nd-magnitude blue star around a zero-magnitude gold star.
15 million years
The Solar System will reach the minimum distance of 27,600 light-years (perigalacticon).  It's in the outer regions of our Milky Way galaxy, orbiting at a mean distance of 29,700 light-years with an orbital eccentricity of 0.07.  The present distance from the center is 27,700 light-years.
40 million years5,6
Phobos, its orbit slowed by tidal forces resulting from orbiting Mars faster than Mars rotates, falls into Mars.  (Future human intervention might be able to prevent this.)
100 million years11
The Dwarf Sagittarius galaxy, about .1% the size of our galaxy, passes through the Milky Way again.
500 million years14
Due to increasing solar temperatures, enough carbon dioxide (CO2) is absorbed and trapped as limestone that plant life, and by extension animal life, dies out.
750 million years12
The Dwarf Sagittarius galaxy, torn and stretched, gets absorbed into the Milky Way.
1-2 billion years3,14
The sun's luminosity has increased enough to evaporate Earth's oceans and sterilize the planet.  The water vapor that was our oceans escapes into space.  Mars slowly becomes relatively more hospitable.
3-7 billion years3,8,12,13,19
The Milky Way and Andromeda galaxies collide and merge, eventually forming a giant elliptical galaxy.  Supernovae explosions may occur so frequently as a result that the night sky may be bright enough to read by.
5 billion years3,5
Sun leaves main sequence, swelling into a red giant.  In time, the strong solar wind and decreased solar mass will push Earth's orbit out nearly to where Mars' is today.
7 billion years3,5
The sun, a red giant nearly as large as Earth's orbit, now puts out enough heat to melt the ice on Jupiter's moons Callisto, Ganymede, and Europa.  Earth's crust is totally molten and featureless.
10 billion years12,19
Two more of the Milky Way's satellite galaxies, the Large and Small Magellanic Clouds, merge into it.
35 billion years7
The sun evolves from a white dwarf into a "dead" black dwarf.
50+ billion years5
Assuming the Earth-moon system is still intact, Earth becomes tidally locked with the moon.  The lunar month and Earth day are now both equal, about 50 present days long.
100 billion years3,4
Large galactic clusters evaporate galaxies through chaotic interactions.
100+ billion years3
Over the next few trillions of years, galactic clusters will coalesce into "supergalaxies."
1 trillion years3,4
Stars cease to form from nebulae; all massive stars have become either neutron stars or black holes.
10 trillion years3
The longest lived of stars shining today, red dwarfs, use the last of their fuel and become white dwarfs.  For a few billion years at the end of their lifetimes, they may have appropriate luminosity & temperature to allow for life on nearby planets.
trillion years3,4
Universal hydrogen reserves are drained.  The last of the red dwarfs die out.  All star production shuts down forever, and the universe goes dark.
1015-17 years3,4
Stellar collisions and near-misses detach dead planets from dead stars.
1016 years9
Lone stars are occasionally formed by the collision of brown dwarfs.
1017 years4
White dwarfs cool to black dwarfs at 5 K.  Proton decay (if any) will keep dwarfs at this temperature for 1030 years.
1019-20 years3,4
Dead stars (brown & black dwarfs, and neutron stars) and planets evaporate from supergalaxies via chaotic interactions.  (90-99% of all stars will evaporate; 1-10% will collect in galactic centers to form gigantic black holes).
1019 years4
Neutron stars cool to 100 K.
1020 years3
Up until now, two brown dwarfs would on rare occasion merge to form a red dwarf.  Beyond this time they're simply scattered way too far apart.
1021 years9
One-solar-mass black holes begin to evaporate as the cosmic background temperature becomes cooler than them.
1020-24 years3,4,9
Orbits of planets and close binary stars decay via gravitational radiation.
1023 years4
Dead stars evaporate from supergalactic clusters.  (Black dwarfs are at 5 K and neutron stars at 100 K due to proton decay; background radiation has cooled to 10-13 K.)
At this stage matter consists of about 90% dead stars, 9% black holes and up to 1% atomic hydrogen and helium.4
1025 years3
Any remaining dead stars and matter still in orbit around galactic centers spirals in from orbital gravitational decay.
1025 years3
If dark matter can be accounted for with WIMPs (weakly interacting massive particles), black dwarfs will accrete them.  WIMP annihilation inside black dwarfs can keep them heated to 64 K for around 1030 years.
1030 years3
Black holes accrete remaining black dwarfs & neutron stars at the galactic level.
1030 years9
106-solar-mass black holes begin to evaporate as the cosmic background temperature becomes cooler than them.
1032+ years4,9
Protons decay (according to SU(5) GUT).
1032+ years4,9
Dead stars evaporate via proton decay (GUT).  Neutron stars pass through a brief white dwarf stage as neutrons & electrons lose degeneracy, before degrading to hydrogen ice and evaporating.
1033 years3
Black holes accrete remaining black dwarfs & neutron stars at the galactic cluster level.
1034 years4
All carbon-based (indeed, atom-based) life forms become extinct due to a lack of atoms.
At this stage most matter in the universe is in the form of e-, e+, n,`n, g (electrons, positrons, neutrinos, antineutrinos, & photons).4
1035 years9
109-solar-mass black holes begin to evaporate as the cosmic background temperature becomes cooler than them.
1045+ years3,9
Virtual-black-hole mechanisms in quantum gravity allow protons to decay.
1065 years4
Ordinary matter liquefies due to quantum tunneling.
1065-67 years4,9
Solar mass black holes evaporate via Hawking process.
1073-85 years4,9
In closed and flat universes (respectively), most e+ and e- form positronium with atomic radii far larger than our present-day universe.  (In open universe most e+ and e- remain free.)
1083 years3
Million-mass black holes (106 Msol) evaporate via Hawking process.
1099 years3,4
Galactic mass black holes (1011 Msol) evaporate via Hawking process.
10106+ years3
Some positronium formation and decay occurs in an open universe.
10117 years4
In flat and closed universes, positronium decays via cascade, releasing 1022 photons per positronium atom.
10117-141 years4,9
Supercluster mass black holes (1017 Msol) evaporate via Hawking process.
10122 years4
Protons decay via Hawking process (if not from SU(5) GUT or other).
10140-150 years9
Tunneling between different vacuum states in the electroweak theory allows protons to decay.
1010-1000?? years9
A cosmological phase transition reconstructs the universe, rewriting the laws of physics, changing universal constant(s), and/or collapsing a spacial dimension.
101500 years4
If ordinary matter survives decay via GUTs or Hawking process (rather unlikely), it decays into iron.
101026 years4
All iron collapses into black holes.  The universe is huge, empty, and desolate beyond imagination.

Based on info from:
1ASTR 103:  Figures for Supplement 1., Fig. 1.7.
2"Lanterns Along the Sun's Way" by Fred Schaaf, Sky & Telescope, Aug. 1998, p. 98.
3"The Future of the Universe" by Fred C. Adams & Gregory Laughlin, Sky & Telescope, Aug. 1998, pp. 32-39.
4Table 10.2 in The Anthropic Cosmological Principle (pp. 653-4) by John D. Barrow and Frank J. Tipler, and Anders Sandberg's Timescale.
5[sci.astro] Solar System (Astronomy Frequently Asked Questions) (5/8).
6A. T. Sinclair (1989, Astronomy & Astrophysics, vol. 220, p. 321).
7The Observatory:  Stars.
8AstroFile -- Future Fate of the Milky Way Galaxy.
9"The Five Ages of the Universe," by Fred Adams and Greg Laughlin, The Free Press, 1999.
10Astronomy Picture of the Day, 9/14/99.
11Astronomy Picture of the Day, 2/16/98.
12A Tourist's Guide to the Milky Way.
13Astrophysicist Maps Out Our New Galaxy.
14Date set for desert Earth.
15Six billion miles and counting....
16Astronomy Picture of the Day, 12/11/99.
17Close Approaches of Stars to the Solar System.
18Astronomy Picture of the Day, 4/11/00.
19Lecture Notes for AST201: Normal Galaxies.

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