If the sun suddenly disappears, how long can the earth last?

If the sun suddenly disappears, how long can the earth last?

"Everything grows on the sun". As the only star in the solar system that can continuously give energy to the earth, the sun plays an irreplaceable role in maintaining the stability of the overall temperature of the earth and promoting the normal survival and smooth reproduction of various creatures. Although the solar radiation energy that the earth can receive only accounts for one billion of the total solar radiation energy, it is extremely precious to the earth, especially to the creatures on the earth. However, all the stars in the universe, like the creatures on earth, have the development and evolution law of "birth, aging, illness and death". If the sun is "old" and no longer emits light and heat, what will happen to the earth?

There are two issues that need to be explained first. Of course, before answering this question, we need to clarify two facts in advance: First, the sun can't suddenly disappear. According to its proper evolutionary trajectory, its main sequence cycle is still more than 3 billion years, and it will take another 2 billion years to evolve into a white dwarf. Even at the stage of red giant star and white dwarf star, it will radiate energy, but after the stage of white dwarf star, there will be no nuclear fusion inside.

The second fact is that even if the sun disappears, there is no problem that the earth can support Takuya. As a planet, its formation process is inseparable from the credit of stars. Once formed, unless it is hit by other giant planets with similar mass or swallowed by black holes, it will exist in space for a long time and will not be fundamentally changed by the shining of stars. Without a star, it would become a rogue planet, and there are many such planets in the universe. To be sure, if there is no sun, the earth will be fine, but all kinds of creatures on the earth will suffer, so the question in the topic will be changed to how long life on the earth can last.

The main reason why the sun releases light and heat is that the nuclear fusion reaction will continue inside the sun. In the early days of the birth of the sun, under the influence of gravitational disturbance, a large number of interstellar matter in the solar system will slowly gather in a core. This gathering process will spread more and more widely with the accumulation of matter in the core area, and finally more than 99% of interstellar matter within the effective gravity range will collapse to the core under the increasing gravity.

In the process of collapse, interstellar matter expands and rubs constantly, and the internal energy of interstellar matter composed of kinetic energy and gravitational potential energy is gradually transformed into heat energy after collapse, which promotes the continuous increase of temperature and pressure in the core area. When the temperature and pressure reach a certain limit, under the action of quantum tunneling, protons in hydrogen atoms will have a certain probability, which can break through the repulsion of atomic coulomb force and enter other nuclei, thus opening the curtain of proton-proton chain nuclear fusion reaction in the sun.

In the process of nuclear fusion of hydrogen in the sun (including the fusion of helium after hydrogen consumption), new substances with higher atomic number are formed, while gamma photons, neutrinos and a lot of energy are released. Among them, gamma photons are repeatedly absorbed and released by high-concentration ionic substances in the sun to varying degrees, so the energy they carry will be attenuated to varying degrees. The longest photon may take 65,438+million years to escape from the sun. Finally, electromagnetic waves with different frequencies form sunlight and release it into space.

Because the density of matter in space is extremely low, heat is basically transferred in the form of thermal radiation, and the transferred energy is absorbed by the matter on the surface of the planet, thus improving the internal energy of these substances to form atoms or molecules, and the surface temperature of the planet will also rise accordingly.

The sun has entered the main sequence period for 5 billion years. For such a long time, it can release energy continuously and stably. On the one hand, it is attributed to the rich hydrogen substances involved in nuclear fusion in the sun. The mass lost by nuclear fusion is about several million tons per second, but this is insignificant compared with its total mass.

The second aspect is that the degree of internal nuclear fusion of stars with solar mass is in the middle and lower level among all stars, and the rate of "burning" is not very intense. Unlike some massive stars, such as those in the central region of the Milky Way, many of them have much greater mass than the sun, but their life span is much shorter than that of the sun, which basically ends in tens of millions of years.

The third aspect is the stability maintenance mechanism of the sun itself. In the main sequence period, the outward radiation pressure of the sun due to nuclear fusion and the inward attraction of the outer layer are basically in a relatively balanced state. Even if there is a slight fluctuation, the internal temperature and pressure will remain in a relatively stable state through self-adjustment function, ensuring that the light and heat released to the outside are always in a constant state.

Because of the mass of the earth, the "heat preservation" mechanism of the earth will not change obviously after the sun disappears (whether it really disappears completely or does not generate heat), so the gravity of the earth can still effectively bind the atmosphere and various substances on the earth, so the composition and structure of the earth will not change obviously. In this context, a series of "heat preservation" mechanisms of the earth can ensure that the temperature of the earth will not suddenly drop to a very low level because of the sudden disappearance of the sun, and this buffer can last for a long time.

There are several factors that push the earth to form an effective "heat preservation" mechanism: First, the earth's atmosphere. Its ability to absorb long-wave radiation is much stronger than that of short-wave radiation, and the energy released by the earth mainly exists in the form of long-wave radiation. Therefore, even without the energy input of solar radiation, due to the existence of the atmosphere, it can strongly absorb long-wave radiation from the earth, and at the same time return part of the absorbed radiation to the surface, which is equivalent to covering the earth with a quilt.

The second is the liquid water of the earth. The specific heat capacity of liquid water is generally much higher than that of solid matter, which means that the energy for storing heat is stronger. 70% of the earth is covered by the ocean, which contains a lot of heat. At the same temperature, the energy released by the ocean is much higher than that released by the land. Under the action of atmospheric circulation, when the earth loses its energy input, this heat will gradually transfer from the ocean to the land, so that the overall temperature of the earth will not suddenly drop out of control. Without the sun, the sea water on the earth can last at least 10 days before it drops from normal temperature to freezing point.

Third, there is a heat source inside the earth. The earth's core contains a lot of radioactive substances, such as uranium 235, uranium 238 and thorium 232. During the decay of these radioactive materials, the corresponding heat will be released continuously for a long time. Moreover, according to the structure of the inner circle of the earth, from the innermost core to the middle mantle and then to the outermost crust, the material state is solid, solid-liquid mixture, highly viscous magma and solid, and the depth of the outermost solid rock stratum can reach thousands of kilometers. This structure also plays a good role in heat preservation, which makes the heat from the inner core dissipate slowly.

After the sun disappears, how long can humans on earth live? Although the earth has the above three important "heat preservation" mechanisms, the disappearance of the sun as the only external energy input source is still a huge disaster for life on earth, including human beings. After all, we can't replicate such a "heat source" in the sky.

Within eight minutes after the sun disappeared, we didn't feel anything on the earth, because the highest propagation speed was the speed of light, no matter the change of light or gravitational waves. Only eight minutes after the sun disappears will we really feel the difference, and then the earth will enter endless darkness.

When this darkness lasts about 1 week 10 days, the temperature of the earth's surface will slowly drop to about 0 degrees Celsius, and all kinds of liquid water on the earth, including rivers, lakes and oceans, will gradually enter the frozen period, no longer having the advantage of high specific heat capacity, and then the temperature of the earth will show a sharp decline trend. At this stage, many plants on the earth have almost withered and disappeared because they have no energy source for photosynthesis. Only the larger plants have strong buffering capacity and barely support their activities, and the oxygen content in the earth's atmosphere has gradually decreased.

When the sun disappears 1 year, the temperature of the earth's surface will drop to between-150 and -200 degrees. Because the core will continue to dissipate heat, the overall temperature of the earth will not continue to drop. The oxygen content in the earth's atmosphere is further reduced, and the surface is no longer suitable for human survival. At this time, it must be moved underground to rely on the heat emitted by the earth's core for "heating", and at the same time, oxygen supply should be considered. It is imperative to develop and use large-scale oxygen-making equipment.

If humans can't find suitable other planets and don't have the conditions for interstellar migration, they can only spend a long time in the dark underground until the earth's core is completely cooled and human civilization comes to an end. The creatures that can accompany human beings on the earth can only be anaerobic creatures at the bottom of the deep sea, relying on the heat released to survive.

Of course, we humans can't wait for the day when the sun disappears. In the process of solar evolution, at the stage of red giant, a helium flash is enough to peel off the earth's atmosphere. What if the sun disappears? Billions of years later, if human beings still exist, with the continuous development of science and technology, perhaps human beings have immigrated to the planet in advance.

What would the earth look like if the sun suddenly disappeared?

Eight minutes after the sun disappears, the earth will lose its sunlight and fall into darkness. Humans can only use electric energy to ignite or make a fire. Without the reflection of the sun's light, other planets will disappear in the darkness one by one, and we will never see the splendid solar system again. When the sun disappears, the gravity on the earth will also disappear. The earth will go into space at a speed of 29 kilometers per second. If the earth does not collide with any other planet or asteroid and is not sucked into a black hole, it will move in a straight line for 4300 years until it enters the orbit of another star. Plants need sunlight for photosynthesis. Without the sun, most small plants on the earth will die in a few days, while larger plants can survive for several years to decades through their own slow metabolism, but we will not face hypoxia for the time being, and the remaining oxygen is enough for humans and animals to breathe for another thousand years.

If there is no heat source in the first week after the sun disappears, the earth will soon cool to about 0 degrees Celsius, but considering the fuel we have, in the first few months, without the sun, we can still rely on the remaining fuel on the earth to keep warm.

In the first year after the sun disappeared, the average temperature of the earth dropped to MINUS 150 degrees, but it was not the lowest until it stabilized at MINUS 240 degrees. If we can't leave the earth and find a livable planet, the only way for us and other creatures to survive is to go deep underground and get close to the core, but this requires a lot of excavation work. In extreme cases, the ocean surface will become a huge skating rink, but it just looks like the ice may be thin. In any case, liquid water on the earth will continue to exist for billions of years, because the temperature of the core is still very high, and deep-sea animals living in the deepest part of the seabed, such as Mariana Trench, can survive for a long time, because they don't need photosynthesis, and as long as water is liquid, they can meet their living conditions.

The sun is a star, and now it is about 4.57 billion years old, and it is still in the stable period of nuclear fusion. We can describe it as middle age. At this stage, the sun can release light and heat stably, and the surface temperature changes little. However, with the continuous combustion of hydrogen and helium in the sun, the sun will shrink by gravity, which will lead to the continuous expansion of the sun's periphery and the continuous contraction of the interior, releasing a lot of light and heat. According to its mass, scientists estimate that the life of the sun is about 5 billion years. After 5 billion years, the sun will begin to carry out helium nuclear fusion, and its volume will expand violently to form a red giant. Eventually, the outer layer of the sun will break away from gravity and spread into space, becoming a planetary nebula. Because there is no radiation pressure generated by nuclear fusion reaction to resist gravitational collapse, the core of the sun will be compressed into a white dwarf by gravity, and the average density is 654.38+00000 times that of liquid water. If there was still the earth, it would continue to revolve around the sun that became a white dwarf.

During the death of the sun, the fate of the earth is uncertain. When the sun becomes a red giant, its radius will be 200 times that of the present, and the surface may extend to the present earth orbit. However, at the same time when the sun becomes a red giant, due to the influence of the solar wind, the sun has lost 30% of its mass, and the gravity of the earth and other nearby planets will weaken, so the earth's orbit will move outward. If so, the earth can survive after the death of the sun. But even if the earth can escape the fate of being burned by the sun, the water on the earth may be evaporated, most of the gas will escape into space, and the surface temperature of the earth will rise, and all living things will be doomed to extinction.

And these will happen in 1 100 million years. In about 10 billion years, the heat of the sun will be about 10% hotter than it is now. For the earth, this is a disaster. As we all know, Venus and the Earth are in a livable zone in the solar system, but the surface temperature of Venus is over 400 degrees, and the Earth will probably become the second Venus in10 billion years. The earth's ecosystem will also collapse completely. This is only the beginning of the aging of the sun, and the radiation and heat will increase more violently in the future. After 65.438 billion years, a flare of the sun will destroy all satellite communications on the earth. As the sun grows older, it will flash helium, just like on the wandering earth. How horrible is this? The earth's natural umbrella, the atmosphere, will also be completely destroyed under the attack of helium flash. At that time, the earth will completely become a fireball, and there is no way to breed life.

So, where will mankind go in the future? Perhaps in the future, human beings will discover other livable planets for interstellar migration.

The sun is the absolute old "big" of the solar system, accounting for 99.8632% of its mass. Its great gravity binds other stars in the solar system around it.

Figure: Schematic diagram of the solar system

Of course, the sun can't suddenly disappear, and of course it can be assumed that this happens.

After the sun disappears for about 8 minutes 19 seconds (average time), people on the earth will feel extremely dark, and at the same time, the earth will lose the bondage of the sun's gravity and fly out of the solar system at a speed of about 29.78 kilometers per second, just like throwing a hammer.

The earth has become an interstellar planet. Interplanetary planets are celestial bodies with planetary mass but not orbiting stars. There are actually many such planets. It is estimated that there are twice as many interplanetary planets as Jupiter. The moon will also follow the earth and remain a satellite of the earth.

Figure: imaginary map of interstellar planets

Without sunshine, the temperature of the earth will drop rapidly. The background radiation temperature of the universe is about 3k. Will the temperature of the earth drop to this temperature? The answer is no! The temperature will be much higher than this.

Because the earth's atmosphere will not disappear, a dense atmosphere will prevent the rapid loss of the earth's temperature on a large scale. About 80% of the heat in the core is provided by isotope decay, so the earth itself will provide a lot of heat. Isotopic decay of the earth's core can provide heat for billions of years. The moon has not been lost, and tidal force will make the earth's matter rub and provide some heat. The temperature of the earth's surface will cool to about MINUS 100 degrees.

The ocean will freeze. The ice layer may be thousands of meters thick, but the lower layer will also be liquid water. There may still be life around submarine volcanoes.

If humans knew all this before the sun disappeared 10 years ago and developed a nuclear fusion reactor, humans could still survive. You can build caves thousands of meters deep underground and use nuclear fusion and geothermal energy to provide energy. Human civilization can even continue to develop. ...