Timeline of the far future (Astronomical)
The timelines displayed here cover events from the beginning of the 11th millennium to the furthest reaches of future time. A number of alternative future events are listed to account for questions still unresolved, such as whether humans will become extinct, whether protons decay, and whether the Earth survives when the Sun expands to become a red giant.
The red supergiant star Antares will likely have exploded in a supernova. The explosion is expected to be easily visible in daylight. (1,000 000 for Betelgeuse)
The small red dwarf Ross 248 will pass within 3.024 light-years of Earth, becoming the closest star to the Sun. It will recede after about 8,000 years, making first Alpha Centauri again and then Gliese 445 the nearest stars.
The proper motion of stars across the celestial sphere, which is the result of their movement through the Milky Way, renders many of the constellations unrecognisable.
Desdemona and Cressida, moons of Uranus, will likely have collided.
Maximum estimated time before the moon Phobos collides with Mars.
Tidal acceleration moves the Moon far enough from Earth that total solar eclipses are no longer possible.
There is a roughly 1-in-100,000 chance that the Earth might be ejected into interstellar space by a stellar encounter before this point, and a 1-in-3-million chance that it will then be captured by another star. Were this to happen, life, assuming it survived the interstellar journey, could potentially continue for far longer.
Neptune’s moon Triton falls through the planet’s Roche limit, potentially disintegrating into a planetary ring system similar to Saturn's
Median point by which the Andromeda Galaxy will have collided with the Milky Way, which will thereafter merge to form a galaxy dubbed “Milkomeda”. The planets of the Solar System are expected to be relatively unaffected by this collision.
With the hydrogen supply exhausted at its core, the Sun leaves the main sequence and begins to evolve into a red giant.
The Earth and Moon are very likely destroyed by falling into the Sun, just before the Sun reaches the tip of its red giant phase and its maximum radius of 256 times the present-day value. Before the final collision, the Moon possibly spirals below Earth's Roche limit, breaking into a ring of debris, most of which falls to the Earth’s surface. During this era, Saturn’s moon Titan may reach surface temperatures necessary to support life. 7.9 billion years: The Sun reaches the tip of the red-giant branch of the Hertzsprung–Russell diagram, achieving its maximum radius of 256 times the present-day value. In the process, Mercury, Venus, and very likely Earth are destroyed.
The Universe’s expansion causes all galaxies beyond the former Milky Way’s Local Group to disappear beyond the cosmic light horizon, removing them from the observable universe.
Expected time when the net light emission from the combined “Milkomeda” galaxy begins to decline as the red dwarf stars pass through their blue dwarf stage of peak luminosity.
1014 (100 trillion years)
High estimate for the time until normal star formation ends in galaxies. This marks the transition from the Stelliferous Era to the Degenerate Era; with no free hydrogen to form new stars, all remaining stars slowly exhaust their fuel and die.
Estimated time until those stars not ejected from galaxies (1%–10%) fall into their galaxies’ central supermassive black holes. By this point, with binary stars having fallen into each other, and planets into their stars, via emission of gravitational radiation, only solitary objects (stellar remnants, brown dwarfs, ejected planetary-mass objects, black holes) will remain in the universe.
Estimated time for all nucleons in the observable universe to decay, if the hypothesized proton half-life takes its smallest possible value (8.2×1033 years).
Estimated time until a stellar mass black hole with a mass of 3 solar masses decays into subatomic particles by Hawking radiation.
Around this vast timeframe, quantum tunnelling in any isolated patch of the vacuum could generate, via inflation, new Big Bangs giving birth to new universes.
Because the total number of ways in which all the subatomic particles in the observable universe can be combined is 10^10^150 a number which, when multiplied by10^10^10^56, disappears into the rounding error, this is also the time required for a quantum-tunnelled and quantum fluctuation-generated Big Bang to produce a new universe identical to our own, assuming that every new universe contained at least the same number of subatomic particles and obeyed laws of physics within the range predicted by string theory.
