Article 48: It may take a couple of ‘months’, but Africa’s collision with Eurasia will close the Mediterranean Basin and create a mountain range, similar to the Himalayas, and all the continents on Earth will fuse into a new supercontinent.
50 million YFN: The Californian coast begins to be sub-ducted 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.
50 – 400 million YFN: Estimated time for the Earth to naturally replenish its fossil fuel reserves.
100 million YFN: Earth will have likely been hit by meteorite comparable in size to the one that triggered the K/T extinction, 65 million years ago.
Rotterdam; Credit to Paul Martens
100 million YFN: Future archaeologists should be able to identify an Urban Stratum of fossilized great coastal cities, like Rotterdam and New York, mostly through the remains of underground infrastructure such as building foundations and utility tunnels. (In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics, that distinguish it from other layers.)
230 million YFN: Beyond this time the orbits of the planets become impossible to predict, due to the limitations of the Lyapunov time. The Lyapunov time reflects the limits of the predictability of the system.
240 million YFN: From its present position, Autumn 2015, the Solar System completes one full orbit of the Galactic center, just one year in the life of our senior friend, the Milky Way astronomer. (See Article 7)
250 million YFN: All the continents on Earth may fuse into a supercontinent. Three potential arrangements of this configuration have been dubbed Amasia, Novo-Pangea and Pangea Ultima.
The next Pangea, ‘Pangea Ultima’ will form as a result of the subduction of the ocean floor of the North and South Atlantic beneath eastern North America and South America. This supercontinent will have a small ocean basin trapped at its center.
400–500 million YFN: The supercontinent (Pangea Ultima, Novo-Pangea, or Amasia) will have likely drifted apart.
500–600 million YFN: Estimated time until a massive, hyper-energetic supernova occurs within 6500 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.
The remnant of a star gone supernova; Credit to NASA, Chandra-XRay-Observatory, 2015-01-22
600 million YFN: 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!
Just one more volume to go from now, 2016, onward! (See Articles 15/16.)
800 million YFN: 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 YFN: 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.
How does all this happen?
Since its birth, 4,5 billion years ago, the Sun’s luminosity has very gently increased by about 30%. This is an inevitable evolution which comes about because, as the billions of years roll by, the Sun is burning up the hydrogen in its core. The helium ashes left behind are denser than hydrogen, so the hydrogen/helium mix in the Sun’s core is very slowly becoming denser, thus raising the pressure. This causes the nuclear reactions to run a little hotter. The Sun brightens.
This brightening process moves along very slowly at first, when there is still ample hydrogen remaining to be burnt at the center of the star. But eventually, the core becomes so severely depleted of fuel that its energy production starts to fall, regardless of the increasing density. When this happens, the density of the core begins to increase even more, because without a heat source to help it resist gravity, the only possible way the core can respond is by contracting until its internal pressure is high enough to hold up the weight of the entire star.
Bizarrely, this emptying of the central fuel tank makes the star brighter, not dimmer, because the intense pressure at the surface of the core causes the hydrogen there to burn even faster. The star’s brightening not only continues, it accelerates.
Our Sun is right now about half-way through a very long process of shifting from a mode, where hydrogen is burned in a kernel at its center, to a mode where hydrogen will be burned in a spherical shell, wrapped around an intensely hot, very dense, but quite inert, helium core. Once it makes the transition from core burning to shell burning, it will be entering its twilight years.
As the helium core grows, so does the hydrogen-burning shell above it, thus making the Sun ever brighter, even while ominously increasing the rate at which helium is accreted onto the core. The growing core burns the Sun’s hydrogen yet more rapidly, which in turn only enlarges the core more rapidly. . . .
In short, in the end, the nuclear furnace at the center of every star begins to overheat. To put numbers on this, when the Sun was formed 4,5 billion years ago, it was about 30% dimmer than at present. At the end of the next 4,8 billion years, the Sun will be about 67% brighter than it is now.
In the 1,6 billion years following that, the Sun’s luminosity will rise to a lethal 2,2 L☉. (L☉ = Luminosity present Sun.) The Earth by then will have been roasted to bare rock, its oceans and all its life boiled away by a looming Sun, that will be some 60% larger than at present. The surface temperature on the Earth will be in excess of 600 F°. But even this version of the Sun is still stable and golden, compared to what is to come…
Around the year 7,1 billion AD, the Sun will begin evolving so rapidly that it will cease to be a main-sequence star. Theoretical calculations indicate that a critical point will be reached when the Sun’s inert helium core reaches about 13% of a solar mass, or about 140 Jupiters. At this point in its life, the Sun will become unruly. The mechanism that has been slowly making it brighter for the past eleven billion years – more core pressure, yielding hotter nuclear burning, yielding more helium to enlarge the core – is now accelerated to disastrous levels by a steadily increasing electrondegeneracy.
500 Million years after it hits the critical point, the Sun’s luminosity will balloon to 34 L☉, fiery enough to create glowing lakes of molten aluminum and copper on the Earth’s surface. In only 45 million years more it will reach 105 L☉ and 40 million years after that it will leap to an incredible 2300 L☉.
By this time the enormous energy output of the Sun will have caused its outer layers to inflate into a vast, but very tenuous atmosphere, at least the size of the orbit of Mercury and possibly as large as the orbit of Venus. (Think of how violently the water behaves in a pot of rapidly boiling water as compared to that in a gently simmering pot. This is analogous to why the Sun’s atmosphere ‘boils’ outward as its core becomes hotter.)
The huge size of the solar atmosphere and the enormous heat output of the Sun mean that (1) the Earth will have been burnt down to nothing but a seared iron core by this point, if not vaporized altogether – calculations show that it could go either way – and (2) the solar atmosphere will be relatively cool despite the Sun’s tremendous energy output. The Sun will be both red in color and extraordinarily luminous. It will have joined the red giants.
But, didn’t we run much too fast forward?
Thanks to Wikipedia, Timeline of the far future, and to the Science Department of NorthWestern University