It is a well-known fact that the life cycle of our star, the Sun, will one day come to its end. According to scientists, this cycle is about 10 billion years. The current age of our star is approaching 5 billion years. This leads to a very interesting and important question: what exactly happens when the Sun reaches its limit? It all starts with the fact that over time, the star will process all of its hydrogen into helium. Then it will start dying. Fortunately for us, this will not happen soon.
The activity of greenhouse gases will significantly increase
One of the first things that happens after the sun has used up all of its hydrogen is that it gets much brighter. The brighter the star becomes, the more solar energy our planet will receive. Gases in our atmosphere, such as carbon dioxide, methane and nitric oxide, work like a blanket, protecting our planet from the excessive heat of a star and keeping it alive. Since the Sun will actually be working overtime, these gases will have to contain more energy. It will become very hot on Earth, water on it will begin to evaporate and form dense clouds in the atmosphere.
These clouds will protect the Earth from the increased radioactive radiation for some time. However, after some time, too much heat will accumulate on the planet, and the oceans will literally boil. From this moment on, life on Earth will not be able to exist. If by this moment we have not yet died, then in the end we will certainly die from a lack of water and very strong heat.
The sun will expand first …
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The sun will not only become brighter, but also significantly increase in size. As soon as a star has used up all its fuel for a thermonuclear reaction, it will enter another phase of its life cycle. Will become a red giant. Despite the increased size, the actual temperature of stars in the red giant phase is lower than that of other stars - only 2000-3000 degrees Celsius. At first glance, it may seem that this is a lot, but this is if you do not take into account the current temperature of the Sun, which can vary from 5000 to 9000 degrees Celsius.
Despite the fact that this is exactly the fate awaiting our star, the same does not always happen with other stars. More compact ones, for example, which are called red dwarfs, are so weak that when they use up all their fuel, they simply go out. True, the very life cycle of such stars lasts much longer than that of other species. On the other hand, blue and white giants can be so large that they can burn out heavier chemical elements until they eventually develop a solid iron core. After that, they collapse into supernovae.
… and then shrinks
The changes of the Sun will not end there. When the star burns up all the helium, it cannot do the same with carbon and will eventually collapse into a white dwarf. In this phase, the luminary will become much smaller in size compared to its original form.
White dwarfs have a much lower energy reserve, but at the same time have a very long life cycle. Stars of this type will continue to exist in this form for the next billion years, until they eventually turn into so-called black dwarfs. Scientists cannot say for sure how long this process will take, because the universe is not yet old enough for even the first black dwarfs to appear!
Earth's orbit will change
Obviously, by the time our Sun dies, everything on Earth will have already perished, but this does not mean that the planet will stop. When the star reaches the red giant phase, it will expand at least three-quarters of the distance to Earth.
Perhaps you thought that the Earth would then burn out to the ground. But surprisingly, it will not be like that at all. With the expansion of the Sun and its approach to our planet, the gravitational forces of the Earth and other neighboring planets will weaken. This weakening will cause the planets to move away from the Sun and take safer orbits. For Mercury and Venus, fate will be much sadder - they will simply be devoured. Of course, all life forms on our planet will have disappeared by this time, therefore such a “escape” of the planet will be virtually meaningless.
Life may appear on other planets
As noted above, by the time the Sun turns into a red giant, life on Earth will disappear, but this does not exclude the possibility that it can appear somewhere else. Jupiter and Saturn are two giant planets with many satellites that can become habitable.
Satellites such as Europa and Ganymede seem to be the most suitable. Yes, now they are completely covered with ice (there is generally a subsurface ocean on Europe, according to the reports of astronomers), but with an increase in the size of the Sun, the area of influence of its light will increase, which can melt this ice, thereby creating an environment suitable for the existence of the familiar life forms.
The death of the sun will be accompanied by a more significant galactic event
Of course, this event will not be caused by the death of our Sun, but will occur simultaneously with it. The Milky Way and Andromeda are moving towards each other at a speed of 402,000 kilometers per hour. Both galaxies will meet exactly when the life of our star comes to an end. A collision is inevitable. The event of a collision of such gigantic cosmic structures, of course, can frighten, but in reality our solar system, including the sun itself, will not be affected by this event, and they will be fine.
True, everything will be in order only until the moment when the star decides to complete its life cycle. Its phase transition will continue after one new one appears on the basis of two galaxies. If it turns out that somehow life will be preserved anywhere in our system, then we can only assume what an amazing picture of colliding gases and stars will be visible to her in the night sky.
It will get warmer at the outer edges of the solar system
We have already said that the Sun will become larger and brighter at some point in the process of its death. This will lead to the fact that the planets located closer to it will turn into scorched wastelands, but what will happen to the planets and dwarf planets that are now "freezing" in the distance?
Take Pluto, for example. Right now, temperatures on this dwarf planet range from -233 to -223 degrees Celsius. But as soon as the radius of the Sun increases, Pluto, like other distant planets and cosmic bodies, will be able to receive heat from it. It is unlikely that as a result of this, life may appear on these planets, since heat alone will not be enough for this, but it will indeed become much warmer on them.
True, everything will change when the Sun turns into a white dwarf. But at least by that time, the outer borders of the solar system will also be able to feel the warmth of our star at least once.
People on Earth will definitely not survive
Perhaps life by the time of the death of the Sun will appear somewhere else, but on Earth its days will be reckoned unconditionally. Unfortunately, everything that we worked and built on will be destroyed along with the death of our star. The surface of the planet will become so hot that it will be impossible to live on it. Even if we somehow create some kind of technology to protect against extreme temperatures, we will still hardly be able to grow something for food, however, we will not have access to water either. Absolutely everything that is necessary for survival will cease to exist.
In general, to some extent it is strange to imagine that by this time absolutely everything will have lost its meaning. That is why we can only hope that somewhere else life can start all over again. It is highly unlikely that she will look or even resemble the human race. And even if it possesses similar features, it will take at least several more billion years for life forms to develop at least to our level today.
Asteroids will leave our system
We are all already accustomed to the fact that there are many different asteroids in our solar system. But all of them, with the death of the Sun and the transition to the white dwarf phase, will also face a serious problem. By this time, Jupiter and other distant planets will already change their orbits due to radical changes associated with our star. Since Jupiter has a huge mass, it will most likely become the center of mass in the system. It has a very powerful gravitational force. It will be quite enough to change the orbits of asteroids, and some of them even to be thrown out to the limits of the solar system. These cosmic boulders can also be thrown towards a white dwarf, or simply ground into dust by gravitational changes.
Scientists are able to make such predictions by observing pre-existing white dwarf stars. While there are many more details to be figured out about the Sun when it enters this phase, scientists noted that the areas around white dwarfs contain a lot of dust. This, most likely, is direct evidence that earlier some solid cosmic bodies could be near the star, which, with the death of their stars, turned into what astronomers saw.
People might try to find another chance
It is difficult to try to predict what level of technology we will be able to achieve in the future, but it is quite interesting to imagine such possibilities. We are already getting close to seeing self-driving cars and other futuristic vehicles on public roads. Perhaps by the time everything goes very badly for our solar system, we will already be able to develop ways to travel long distances in space. We already know the places that could be inhabited, so when the time comes, we could go there. It is quite possible that by that time our race will already be able to turn into an interplanetary species and populate many other solar systems.
Today's news talks about NASA preparing for a flight to Mars. Many other companies, both private and public, also express their desire to become the first colonizers of the Red Planet. If such a mission really succeeds, then for the human future it will become a real revolution. Of course, the flight to Mars and its settlement will not be as large-scale as it could be with the settlement of another galaxy or at least the solar system, but, as Neil Armstrong once said, “This is a small step for man and a huge leap for everything humanity.
We can only hope that we can avoid catastrophic events until the moment we have a chance to engage in the colonization of the universe. Most of what is "there" remains unknown to us. Even our telescopes are not yet powerful enough to see the features of certain planets in other systems. In most cases, everything is done on the basis of predictions and data analysis. We do not yet know all the scales of the Universe, as well as the scale of all our capabilities. But even if the death of the Sun now may seem to us as the death of all that living, that we know, in fact it may not be so. The only thing that we know, or at least very much would like to hope for, is that our minds will be able to send us into the Universe much further than we can now imagine.
Nikolay Khizhnyak