# Timeline of the far future

Last updated on 24 May 2017

While predictions of the future can never be absolutely certain, present understanding in various fields allows for the prediction of far-future events, if only in the broadest outline. These fields include astrophysics, which has revealed how planets and stars form, interact, and die; particle physics, which has revealed how matter behaves at the smallest scales; evolutionary biology, which predicts how life will evolve over time; and plate tectonics, which shows how continents shift over millennia.

All projections of the future of the Earth, the Solar System, and the Universe must account for the second law of thermodynamics, which states that entropy, or a loss of the energy available to do work, must increase over time. Stars will eventually exhaust their supply of hydrogen fuel and burn out. Close encounters gravitationally fling planets from their star systems, and star systems from galaxies.

Eventually, matter itself is expected to come under the influence of radioactive decay, as even the most stable materials break apart into subatomic particles. Current data suggest that the universe has a flat geometry (or very close to flat), and thus, will not collapse in on itself after a finite time, and the infinite future potentially allows for the occurrence of a number of massively improbable events, such as the formation of a Boltzmann brain.

The timelines displayed here cover events from the beginning of the 11th millennium to the furthest reaches of future time. A number of alternate future events are listed to account for questions still unresolved, such as whether humans will become extinct, whether protons decay, or whether Earth will survive the Sun's expansion into a red giant.

An artist's concept of a charred Earth seven billion years from now, after the Sun has entered the red giant phase

## Key

 Astronomy and astrophysics Geology and planetary science Biology Particle physics Mathematics Technology and culture

## Future of the Earth, the Solar System and the Universe

Years from now Event
10,000 If a failure of the Wilkes Subglacial Basin "ice plug" in the next few centuries were to endanger the East Antarctic Ice Sheet, it will take up to this long to melt completely. Sea levels would rise 3 to 4 meters. (One of the potential long-term effects of global warming, this is separate from the shorter term threat of the West Antarctic Ice Sheet).
10,000 The red supergiant star Antares will likely have exploded in a supernova. The explosion is expected to be easily visible in daylight.
25,000 The northern Martian polar ice cap could recede as Mars reaches a warming peak of the northern hemisphere during the ~50,000 year perihelion precession aspect of its Milankovitch cycle.
36,000 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 (see timeline).
50,000 According to Berger and Loutre, the current interglacial period ends sending the Earth back into a glacial period of the current ice age, regardless of the effects of anthropogenic global warming.

Niagara Falls will have eroded away the remaining 32 km to Lake Erie, and ceased to exist.

The many glacial lakes of the Canadian Shield will have been erased by post-glacial rebound and erosion.

50,000 The length of the day used for astronomical timekeeping reaches about 86,401 SI seconds, due to lunar tides decelerating the Earth's rotation. Under the present-day timekeeping system, a leap second will need to be added to the clock every day.
100,000 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.
100,000 The hypergiant star VY Canis Majoris will likely have exploded in a hypernova.
100,000 Earth will likely have undergone a supervolcanic eruption large enough to erupt 400 km3 of magma. For comparison, Lake Erie is 484 km3.
100,000 Native North American earthworms, such as Megascolecidae, will have naturally spread north through the United States Upper Midwest to the Canada–US border, recovering from the Laurentide ice sheet glaciation (38°N to 49°N), assuming a migration rate of 10 m / year. (However, non-native invasive earthworms of North America have already been introduced by humans on a much shorter timescale, causing a shock to the regional ecosystem).
100,000+ As one of the long-term effects of global warming, 10% of anthropogenic carbon dioxide will still remain in a stabilized atmosphere.
250,000 Lōʻihi, the youngest volcano in the Hawaiian–Emperor seamount chain, will rise above the surface of the ocean and become a new volcanic island.
~300,000 At some point in the next "several" hundred thousand years, the Wolf-Rayet star WR 104 is expected to explode in a supernova. It has been suggested that it may produce a gamma ray burst that could pose a threat to life on Earth should its poles be aligned 12° or lower towards Earth. The star's axis of rotation has yet to be determined with certainty.
500,000 Earth will likely have been hit by an asteroid of roughly 1 km in diameter, assuming it cannot be averted.
500,000 The rugged terrain of Badlands National Park in South Dakota will have eroded away completely.
950,000 Meteor Crater, a large impact crater in Arizona considered the "freshest" of its kind, will have been eroded away.
1 million Earth will likely have undergone a supervolcanic eruption large enough to erupt 3,200 km3 of magma, an event comparable to the Toba supereruption 75,000 years ago.
1 million Highest estimated time until the red supergiant star Betelgeuse explodes in a supernova. The explosion is expected to be easily visible in daylight.
1.4 million The star Gliese 710 will pass as close as 13,365 AU (0.2 light-years to the Sun) before moving away. This will gravitationally perturb members of the Oort cloud, a halo of icy bodies orbiting at the edge of the Solar System, thereafter increasing the likelihood of a cometary impact in the inner Solar System.
2 million Estimated time required for coral reef ecosystems to physically rebuild and biologically recover from current human-caused ocean acidification.
2 million+ The Grand Canyon will erode further, deepening slightly, but principally widening into a broad valley surrounding the Colorado River.
2.7 million Average orbital half-life of current centaurs, that are unstable because of gravitational interaction of the several outer planets. See predictions for notable centaurs.
10 million The widening East African Rift valley is flooded by the Red Sea, causing a new ocean basin to divide the continent of Africa and the African Plate into the newly formed Nubian Plate and the Somali Plate.
10 million Estimated time for full recovery of biodiversity after a potential Holocene extinction, if it were on the scale of the five previous major extinction events.

Even without a mass extinction, by this time most current species will have disappeared through the background extinction rate, with many clades gradually evolving into new forms. (However, without a mass extinction, there will now be an ecological crisis requiring millions of years of recovery).

50 million Maximum estimated time before the moon Phobos collides with Mars.
50 million The Californian coast begins to be subducted into the Aleutian Trench due to its northward movement along the San Andreas Fault.

Africa's collision with Eurasia closes the Mediterranean Basin and creates a mountain range similar to the Himalayas.

The Appalachian Mountains peaks will largely erode away, weathering at 5.7 Bubnoff units, although topography will actually increase as regional valleys deepen at twice this rate.

50–60 million The Canadian Rockies will erode away to a plain, assuming a rate of 60 Bubnoff units. (The Southern Rockies in the United States are eroding at a somewhat slower rate.)
50–400 million Estimated time for Earth to naturally replenish its fossil fuel reserves.
80 million The Big Island becomes the last of the current Hawaiian Islands to sink beneath the surface of the ocean.
100 million Earth will likely have been hit by an asteroid comparable in size to the one that triggered the K–Pg extinction 66 million years ago, assuming it cannot be averted.
100 million Upper estimate for lifespan of the rings of Saturn in their current state.
230 million Prediction of the orbits of the planets is impossible over greater time spans than this, due to the limitations of Lyapunov time.
240 million From its present position, the Solar System completes one full orbit of the Galactic center.
250 million All the continents on Earth may fuse into a supercontinent. Three potential arrangements of this configuration have been dubbed Amasia, Novopangaea, and Pangaea Ultima.
400–500 million The supercontinent (Pangaea Ultima, Novopangaea, or Amasia) will likely have rifted apart.
500–600 million Estimated time until a gamma ray burst, or massive, hyperenergetic supernova, occurs within 6,500 light-years of Earth; close enough for its rays to affect Earth's ozone layer and potentially trigger a mass extinction, assuming the hypothesis is correct that a previous such explosion triggered the Ordovician–Silurian extinction event. However, the supernova would have to be precisely oriented relative to Earth to have any negative effect.
600 million Tidal acceleration moves the Moon far enough from Earth that total solar eclipses are no longer possible.
600 million The Sun's increasing luminosity begins to disrupt the carbonate–silicate cycle; higher luminosity increases weathering of surface rocks, which traps carbon dioxide in the ground as carbonate. As water evaporates from the Earth's surface, rocks harden, causing plate tectonics to slow and eventually stop. Without volcanoes to recycle carbon into the Earth's atmosphere, carbon dioxide levels begin to fall. By this time, carbon dioxide levels will fall to the point at which C3 photosynthesis is no longer possible. All plants that utilize C3 photosynthesis (~99 percent of present-day species) will die.
800 million Carbon dioxide levels fall to the point at which C4 photosynthesis is no longer possible. Free oxygen and ozone disappear from the atmosphere. Multicellular life dies out.
1 billion The Sun's luminosity has increased by 10 percent, causing Earth's surface temperatures to reach an average of ~320 K (47 °C, 116 °F). The atmosphere will become a "moist greenhouse", resulting in a runaway evaporation of the oceans. Pockets of water may still be present at the poles, allowing abodes for simple life.
1.3 billion Eukaryotic life dies out due to carbon dioxide starvation. Only prokaryotes remain.
1.5–1.6 billion The Sun's increasing luminosity causes its circumstellar habitable zone to move outwards; as carbon dioxide increases in Mars's atmosphere, its surface temperature rises to levels akin to Earth during the ice age.
2.3 billion The Earth's outer core freezes, if the inner core continues to grow at its current rate of 1 mm per year. Without its liquid outer core, the Earth's magnetic field shuts down, and charged particles emanating from the Sun gradually deplete the atmosphere.
2.8 billion Earth's surface temperature, even at the poles, reaches an average of ~422 K (149 °C; 300 °F). At this point, life, now reduced to unicellular colonies in isolated, scattered microenvironments such as high-altitude lakes or subsurface caves, will completely die out.
3 billion Median point at which the Moon's increasing distance from the Earth lessens its stabilising effect on the Earth's axial tilt. As a consequence, Earth's true polar wander becomes chaotic and extreme.
3.3 billion One percent chance that Jupiter's gravity may make Mercury's orbit so eccentric as to collide with Venus, sending the inner Solar System into chaos and potentially leading to a planetary collision with Earth. Other possible scenarios include Mercury colliding with the Sun, being ejected from the Solar System, or colliding with Earth.
3.5–4.5 billion The amount of water vapour in the lower atmosphere increases to 40%. This, combined with the luminosity of the Sun reaching roughly 35–40% more than its present-day value, will result in Earth's atmosphere heating up and the surface temperature skyrocketing to roughly 1,600 K (1,330 °C; 2,420 °F), hot enough to melt surface rock. This essentially will make the planet much like how Venus is today.
3.6 billion Neptune's moon Triton falls through the planet's Roche limit, potentially disintegrating into a planetary ring system similar to Saturn's.
4 billion 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.
5 billion With the hydrogen supply exhausted at its core, the Sun leaves the main sequence and begins to evolve into a red giant.
7.5 billion Earth and Mars may become tidally locked with the expanding subgiant Sun.
7.59 billion 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.
7.9 billion 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, very likely Earth, and possibly Mars are destroyed.

During these times, it is possible that Saturn's moon Titan could achieve surface temperatures necessary to support life.

8 billion The Sun becomes a carbon-oxygen white dwarf with about 54.05 percent its present mass. At this point, if somehow the Earth survives, temperatures on the surface of the planet, as well as other remaining planets in the Solar System, will begin dropping rapidly, due to the white dwarf Sun emitting much less energy than it does today.
22 billion The end of the Universe in the Big Rip scenario, assuming a model of dark energy with w = −1.5. Observations of galaxy cluster speeds by the Chandra X-ray Observatory suggest that the true value of w is ~-0.991, meaning the Big Rip will not occur.
50 billion If the Earth and Moon are not engulfed by the Sun, by this time they will become tidelocked, with each showing only one face to the other. Thereafter, the tidal action of the Sun will extract angular momentum from the system, causing the lunar orbit to decay and the Earth's spin to accelerate.
100 billion 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.
150 billion The cosmic microwave background cools from its current temperature of ~2.7 K to 0.3 K, rendering it essentially undetectable with current technology.
450 billion Median point by which the ~47 galaxies of the Local Group will coalesce into a single large galaxy.
800 billion 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.
1012 (1 trillion) Low estimate for the time until star formation ends in galaxies as galaxies are depleted of the gas clouds they need to form stars.

The universe's expansion, assuming a constant dark energy density, multiplies the wavelength of the cosmic microwave background by 1029, exceeding the scale of the cosmic light horizon and rendering its evidence of the Big Bang undetectable. However, it may still be possible to determine the expansion of the universe through the study of hypervelocity stars.

4x1012 (4 trillion) Estimated time until the red dwarf star Proxima Centauri, the closest star to the Sun at a distance of 4.25 light-years, leaves the main sequence and becomes a white dwarf.
1.2x1013 (12 trillion) Estimated time until the red dwarf VB 10, as of 2016 the least massive main sequence star with an estimated mass of 0.075 M, runs out of hydrogen in its core and becomes a white dwarf.
3×1013 (30 trillion) Estimated time for stars (including the Sun) to undergo a close encounter with another star in local stellar neighborhoods. Whenever two stars (or stellar remnants) pass close to each other, their planets' orbits can be disrupted, potentially ejecting them from the system entirely. On average, the closer a planet's orbit to its parent star the longer it takes to be ejected in this manner, because it is gravitationally more tightly bound to the star.
1014 (100 trillion) 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.
1.1–1.2×1014 (110–120 trillion) Time by which all stars in the universe will have exhausted their fuel (the longest-lived stars, low-mass red dwarfs, have lifespans of roughly 10–20 trillion years). After this point, the stellar-mass objects remaining are stellar remnants (white dwarfs, neutron stars, black holes) and brown dwarfs.

Collisions between brown dwarfs will create new red dwarfs on a marginal level: on average, about 100 stars will be shining in what was once the Milky Way. Collisions between stellar remnants will create occasional supernovae.

1015 (1 quadrillion) Estimated time until stellar close encounters detach all planets in star systems (including the Solar System) from their orbits.

By this point, the Sun will have cooled to five degrees above absolute zero.

1019 to 1020 (10–100 quintillion) Estimated time until 90%–99% of brown dwarfs and stellar remnants (including the Sun) are ejected from galaxies. When two objects pass close enough to each other, they exchange orbital energy, with lower-mass objects tending to gain energy. Through repeated encounters, the lower-mass objects can gain enough energy in this manner to be ejected from their galaxy. This process eventually causes the Milky Way to eject the majority of its brown dwarfs and stellar remnants.
1020 (100 quintillion) Estimated time until the Earth collides with the black dwarf Sun due to the decay of its orbit via emission of gravitational radiation, if the Earth is not ejected from its orbit by a stellar encounter or engulfed by the Sun during its red giant phase.
1030 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 planets, black holes) will remain in the universe.
2×1036 The estimated time for all nucleons in the observable universe to decay, if the proton half-life takes its smallest possible value (8.2×1033 years).
3×1043 Estimated time for all nucleons in the observable universe to decay, if the proton half-life takes the largest possible value, 1041 years, assuming that the Big Bang was inflationary and that the same process that made baryons predominate over anti-baryons in the early Universe makes protons decay. By this time, if protons do decay, the Black Hole Era, in which black holes are the only remaining celestial objects, begins.
1065 Assuming that protons do not decay, estimated time for rigid objects, from free-floating rocks in space to planets, to rearrange their atoms and molecules via quantum tunneling. On this timescale, any discrete body of matter "behaves like a liquid" and becomes a smooth sphere due to diffusion and gravity.
5.8×1068 Estimated time until a stellar mass black hole with a mass of 3 solar masses decays into subatomic particles by the Hawking process.
1.342×1099 Estimated time until the central black hole of S5 0014+81, as of 2015 the most massive known with the mass of 40 billion solar masses, dissipates by the emission of Hawking radiation, assuming zero angular momentum (non-rotating black hole). However, the black hole is currently accreting, so the time it takes to dissipate may be longer than this.
1.7×10106 Estimated time until a supermassive black hole with a mass of 20 trillion solar masses decays by the Hawking process. This marks the end of the Black Hole Era. Beyond this time, if protons do decay, the Universe enters the Dark Era, in which all physical objects have decayed to subatomic particles, gradually winding down to their final energy state in the heat death of the universe.
10200 Estimated high time for all nucleons in the observable universe to decay, if they don't via the above process, through any one of many different mechanisms allowed in modern particle physics (higher-order baryon non-conservation processes, virtual black holes, sphalerons, etc.) on time scales of 1046 to 10200 years.
101500 Assuming protons do not decay, the estimated time until all baryonic matter has either fused together to form iron-56 or decayed from a higher mass element into iron-56 (see iron star).
${\displaystyle 10^{10^{26}}}$ Low estimate for the time until all objects exceeding the Planck mass collapse via quantum tunnelling into black holes, assuming no proton decay or virtual black holes. On this vast timescale, even ultra-stable iron stars are destroyed by quantum tunnelling events. First iron stars of sufficient mass will collapse via tunnelling into neutron stars. Subsequently, neutron stars and any remaining iron stars collapse via tunnelling into black holes. The subsequent evaporation of each resulting black hole into sub-atomic particles (a process lasting roughly 10100 years) is on these timescales instantaneous.
${\displaystyle 10^{10^{50}}}$ Estimated time for a Boltzmann brain to appear in the vacuum via a spontaneous entropy decrease.
${\displaystyle 10^{10^{76}}}$ High estimate for the time until all matter collapses into neutron stars or black holes, assuming no proton decay or virtual black holes, which then (on these timescales) instantaneously evaporate into sub-atomic particles.
${\displaystyle 10^{10^{120}}}$ High estimate for the time for the Universe to reach its final energy state, even in the presence of a false vacuum.
${\displaystyle 10^{10^{10^{56}}}}$ 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 ${\displaystyle 10^{10^{115}}}$, a number which, when multiplied by ${\displaystyle 10^{10^{10^{56}}}}$, 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.

## Future of humanity

Years from now Event
10,000 Most probable estimated lifespan of technological civilization, according to Frank Drake's original formulation of the Drake equation.
10,000 If globalization trends lead to panmixia, human genetic variation will no longer be regionalized, as the effective population size will equal the actual population size. (This does not mean homogeneity, as minority traits will still be preserved, e.g., no disappearing blonde gene, but will rather be evenly distributed worldwide.)
10,000 Humanity has a 95% probability of being extinct by this date, according to Brandon Carter's formulation of the controversial Doomsday argument, which argues that half of the humans who will ever have lived have probably already been born.
20,000 According to the glottochronology linguistic model of Morris Swadesh, future languages should retain just 1 out of 100 "core vocabulary" words on their Swadesh list compared to that of their current progenitors.
100,000+ Time required to terraform Mars with an oxygen-rich breathable atmosphere, using only plants with solar efficiency comparable to the biosphere currently found on Earth.
1 million Estimated shortest time by which humanity could colonize our Milky Way galaxy and become capable of harnessing all the energy of the galaxy, assuming a velocity of 10% the speed of light.
2 million Vertebrate species separated for this long will generally undergo allopatric speciation. Evolutionary biologist James W. Valentine predicted that if humanity has been dispersed among genetically isolated space colonies over this time, the galaxy will host an evolutionary radiation of multiple human species with a "diversity of form and adaptation that would astound us". (This would be a natural process of isolated populations, unrelated to potential deliberate genetic enhancement technologies.)
7.8 million Humanity has a 95% probability of being extinct by this date, according to J. Richard Gott's formulation of the controversial Doomsday argument, which argues that we have probably already lived through half the duration of human history.
5–50 million Shortest time by which the entire galaxy could be colonised by means within reach of current technology.
100 million Maximal estimated lifespan of technological civilization, according to Frank Drake's original formulation of the Drake equation.
1 billion Estimated time for an astroengineering project to alter the Earth's orbit, compensating for the Sun's increasing brightness and outward migration of the habitable zone, accomplished by repeated asteroid gravity assists.

## Spacecraft and space exploration

To date five spacecraft (Voyager 1, Voyager 2, Pioneer 10, Pioneer 11 and New Horizons) are on trajectories which will take them out of the Solar System and into interstellar space. Barring an extremely unlikely collision with some object, the craft should persist indefinitely.

Years from now Event
10,000 Pioneer 10 passes within 3.8 light-years of Barnard's Star.
25,000 The Arecibo message, a collection of radio data transmitted on 16 November 1974, reaches the distance of its destination, the globular cluster Messier 13. This is the only interstellar radio message sent to such a distant region of the galaxy. There will be a 24-light-year shift in the cluster's position in the galaxy during the time it takes the message to reach it, but as the cluster is 168 light-years in diameter, the message will still reach its destination. Any reply will take at least another 25,000 years.
32,000 Pioneer 10 passes within 3 light-years of Ross 248.
40,000 Voyager 1 passes within 1.6 light-years of AC+79 3888, a star in the constellation Camelopardalis also known as Gliese 445.
50,000 The KEO space time capsule, if it is launched, will reenter Earth's atmosphere.
296,000 Voyager 2 passes within 4.3 light-years of Sirius, the brightest star in the night sky.
800,000–8 million Low estimate of Pioneer 10 plaque lifespan, before the etching is destroyed by poorly-understood interstellar erosion processes.
2 million Pioneer 10 passes near the bright star Aldebaran.
4 million Pioneer 11 passes near one of the stars in the constellation Aquila.
8 million The LAGEOS satellites' orbits will decay, and they will re-enter Earth's atmosphere, carrying with them a message to any far future descendants of humanity, and a map of the continents as they are expected to appear then.
1 billion Estimated lifespan of the two Voyager Golden Records, before the information stored on them is rendered unrecoverable.

## Technological projects

Years from now Event
10,000 Planned lifespan of the Long Now Foundation's several ongoing projects, including a 10,000-year clock known as the Clock of the Long Now, the Rosetta Project, and the Long Bet Project.

Estimated lifespan of the HD-Rosetta analog disc, an ion beam-etched writing medium on nickel plate, a technology developed at Los Alamos National Laboratory and later commercialized. (The Rosetta Project uses this technology, named after the Rosetta Stone).

100,000+ Estimated lifespan of Memory of Mankind (MOM) self storage-style repository in Hallstatt salt mine in Austria, which stores information on inscribed tablets of stoneware.
1 million Planned lifespan of the Human Document Project being developed at the University of Twente in the Netherlands.
1 billion Estimated lifespan of "Nanoshuttle memory device" using an iron nanoparticle moved as a molecular switch through a carbon nanotube, a technology developed at the University of California at Berkeley.
more than 13 billion Estimated lifespan of "Superman memory crystal" data storage using femtosecond laser-etched nanostructures in glass, a technology developed at the University of Southampton.

## Human constructs

Years from now Event
50,000 Estimated atmospheric lifetime of tetrafluoromethane, the most durable greenhouse gas.
1 million Current glass objects in the environment will be decomposed.

Various public monuments composed of hard granite will have eroded one meter, in a moderate climate, assuming a rate of 1 Bubnoff unit (1 mm / 1,000 years, or ~1 inch / 10,000 years).

Without maintenance, the Great Pyramid of Giza will erode into unrecognizability.

On the Moon, Neil Armstrong's "one small step" footprint at Tranquility Base will erode by this time, along with those left by all twelve Apollo moonwalkers, due to the accumulated effects of space weathering. (Normal erosion processes active on Earth are not present due to the Moon's almost complete lack of atmosphere.)

7.2 million Without maintenance, Mount Rushmore will erode into unrecognizability.
100 million Future archaeologists should be able to identify an "Urban Stratum" of fossilized great coastal cities, mostly through the remains of underground infrastructure such as building foundations and utility tunnels.

## Astronomical events

Extremely rare astronomical events beginning in the 11th millennium AD (year 10,001) will be:

Date / Years from now Event
20 August, AD 10,663 A simultaneous total solar eclipse and transit of Mercury.
25 August, AD 11,268 A simultaneous total solar eclipse and transit of Mercury.
28 February, AD 11,575 A simultaneous annular solar eclipse and transit of Mercury.
17 September, AD 13,425 A near-simultaneous transit of Venus and Mercury.
AD 13,727 The Earth's axial precession will have made Vega the northern pole star.
13,000 years By this point, halfway through the precessional cycle, Earth's axial tilt will be reversed, causing summer and winter to occur on opposite sides of Earth's orbit. This means that the seasons in the northern hemisphere, which experiences more pronounced seasonal variation due to a higher percentage of land, will be even more extreme, as it will be facing towards the Sun at Earth's perihelion and away from the Sun at aphelion.
5 April, AD 15,232 A simultaneous total solar eclipse and transit of Venus.
20 April, AD 15,790 A simultaneous annular solar eclipse and transit of Mercury.
14,000-17,000 years The Earth's axial precession will make Canopus the South Star, but it will only be within 10° of the south celestial pole.
AD 20,346 Thuban will be the northern pole star.
AD 27,800 Polaris will again be the northern pole star.
27,000 years The eccentricity of Earth's orbit will reach a minimum, 0.00236 (it is now 0.01671).
October, AD 38,172 A transit of Uranus from Neptune, the rarest of all planetary transits.
26 July, AD 69,163 A simultaneous transit of Venus and Mercury.
AD 70,000 Comet Hyakutake returns to the inner solar system, after traveling in its orbit out to its aphelion 3,410 A.U. from the Sun and back.
27 and 28 March, AD 224,508 Respectively, Venus and then Mercury will transit the Sun.
AD 571,741 A simultaneous transit of Venus and the Earth as seen from Mars
6 million Comet C/1999 F1 (Catalina), one of the longest period comets known, returns to the inner solar system, after traveling in its orbit out to its aphelion 66,600 A.U. (1.05 light-years) from the Sun and back.

## Calendric predictions

Years from now Event
10,000
The Gregorian calendar will be roughly 10 days out of sync with the seasons.
10,875 10 June, AD 12,892 In the Hebrew calendar, due to a gradual drift with regard to the solar year, Passover will fall on the northern summer solstice (it is meant to fall around the spring equinox).
18,857 AD 20,874 The lunar Islamic calendar and the solar Gregorian calendar will share the same year number. After this, the shorter Islamic calendar will slowly overtake the Gregorian.
25,000
The Tabular Islamic calendar will be roughly 10 days out of sync with the Moon's phase.
46,884 1 March, AD 48,901 The Julian calendar (365.25 days) and Gregorian calendar (365.2425 days) will be one year apart.

## Nuclear power

Years from now Event
10,000 The Waste Isolation Pilot Plant, for nuclear weapons waste, is planned to be protected until this time, with a "Permanent Marker" system designed to warn off visitors through both multiple languages (the six UN languages and Navajo) and through pictograms. (The Human Interference Task Force has provided the theoretical basis for United States plans for future nuclear semiotics.)
20,000 The Chernobyl Exclusion Zone, the 2,600 km2 (1,000 sq mi) area of Ukraine and Belarus left deserted by the 1986 Chernobyl disaster, becomes safe for human life.
30,000 Estimated supply lifespan of fission-based breeder reactor reserves, using known sources, assuming 2009 world energy consumption.
60,000 Estimated supply lifespan of fission-based light water reactor reserves if it is possible to extract all the uranium from seawater, assuming 2009 world energy consumption.
211,000 Half-life of technetium-99, the most important long-lived fission product in uranium-derived nuclear waste.
15.7 million Half-life of iodine-129, the most durable long-lived fission product in uranium-derived nuclear waste.
60 million Estimated supply lifespan of fusion power reserves if it is possible to extract all the lithium from seawater, assuming 1995 world energy consumption.
5 billion Estimated supply lifespan of fission-based breeder reactor reserves if it is possible to extract all the uranium from seawater, assuming 1983 world energy consumption.
150 billion Estimated supply lifespan of fusion power reserves if it is possible to extract all the deuterium from seawater, assuming 1995 world energy consumption.

## Graphical timelines

For graphical, logarithmic timelines of these events see:

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