What are the endings of life on earth?

The sun is gradually consuming its nuclear energy, but surprisingly, it is getting brighter and brighter. This process happened so slowly that we didn't notice it at all. With the gradual consumption of hydrogen in the sun's core, it will shrink slightly, leading to the increase of core pressure and temperature. The efficiency of nuclear reaction depends largely on the temperature of the core, so fuel consumption will also accelerate. After 65.438 billion years, the sun will be so hot that the climate on the earth will become extremely hot, and the habitable area on the earth will have to be far away from the equator and shrink to the poles.

But this can only provide short-term shelter. As the low latitudes become uninhabitable, the desert will begin to expand, and the land area suitable for crop cultivation will be seriously insufficient. The drift of the continental plate has destroyed the shape of the continent that we are familiar with now. Any existing ice sheet will melt, causing the sea level to rise sharply and most of the land will be submerged.

The temperature is still rising relentlessly and will reach the critical point in the next 3 billion years. The sun will be 40% brighter than it is now, so all the water on the earth's surface will evaporate and the ocean will disappear, and our world will become a purgatory under the scorching sun.

If human beings still exist under such drastic changes in the earth's environment, how will these distant descendants respond? The first sign of these changes will be detected and the alarm will sound, but even a highly developed civilization is unlikely to control the sun. There is no doubt that the Climate Change Response Committee will hold a meeting, but what should be written on the agenda? It may be feasible to move the earth to a safer place, but as we will talk about later, this is not a permanent solution. Maybe we can remove the whole earth from the solar system and try to make it self-sufficient, so that life can survive without the sun. If this is too difficult to achieve, humans may consider emigrating to other places on a large scale-to another solar system, or building a huge, self-sufficient space station to accommodate survivors.

If mankind can only do nothing, with the passage of time, the whole earth is likely to become a molten and boiling magma world. Everything will not be spared, and eventually all living things will be written off. Mars will become much hotter than it is now, and its huge polar cap (composed of carbon dioxide and water) will begin to melt. The atmosphere has also begun to form, and in a very short time-about tens of millions of years, Mars will temporarily become a livable place. But this environment will not last long. Mars is too small and weak in gravity to keep the newly formed atmosphere on its surface for a long time.

It has been suggested that humans can find a refuge-Titan, Saturn's largest satellite, which has a dense atmosphere rich in nitrogen. Unfortunately, this is by no means the case. The escape velocity of the atmosphere on Titan's surface is very low. The reason why the atmosphere can be maintained is because it is very cold, because at low temperature, the movement velocity of gas molecules is also very low. If the temperature rises even a few degrees, Titan's entire atmosphere will disappear without a trace.

In the next 500 million years, the sun will expand twice as big as it is now. Although the surface temperature will decrease, its luminosity will double. Earth's orbit will also be affected. The stellar wind from the sun will be greatly enhanced, and the mass will be continuously lost, and it will enter the red giant stage. Smaller mass means that the gravity of the sun will weaken, and accordingly, the orbit of the planet will expand outward. The earth will move 200 million kilometers away from the sun-of course, it is still far from escaping from the scorching sun.