Why can the sun burn for five billion years? What kind of fuel does it use?

The existence of all things is inseparable from energy, whether it is plants or animals or other simple life, their survival needs energy to support. The earth is a life world rich in species. In addition to intelligent life, there are millions of species.

So how does the energy needed for life on earth come from? Apart from a small part of the energy inside the earth, most of it comes from the sun above us. For people in ancient times, it is not clear what the sun is. In the eyes of the ancients, the sun is sacred and no one is great, so many legends about the sun were born.


After entering the era of science and technology, with the help of science and technology, we began to constantly recognize the earth and the world beyond the earth. At this time, we finally understand what the sun is? In fact, the sun is not mysterious. It is very common in the universe. Like the earth, it is also a celestial body in the universe, but because of its huge mass, it has become a star that can release huge energy.

The existence of the sun leads to the solar system. The energy source of the whole solar system is mainly the sun. The formation of the earth ecosystem, the birth of life, evolution and survival are inseparable from the energy of the sun. In fact, the energy release of the sun is also a kind of combustion, but in our cognition, combustion needs oxygen and fuel, which is often a short-term energy release.

However, the burning time of the sun is very long. According to the research of scientists, the sun was formed 5 billion years ago, and it has been burning for 5 billion years now. By solar mass standards, it can continue to burn for about five billion years. Why can the sun burn for five billion years? What kind of fuel does it use.


The burning of any substance needs fuel. Once there is no fuel, the fuel process will end, and so will the sun. Since the sun can burn for 5 billion years, its fuel must be different. Is that true?

In fact, the fuel that the sun needs to burn is very simple and common. It is hydrogen, which accounts for most of the elements in the universe. As we all know, the universe originated from the singularity big bang 13.8 billion years ago. After the big bang, the universe was born. In the process of instantaneous energy release, protons, neutrons, electrons and other basic particles gradually formed.


By 380000 years after the big bang, the atomic structure was formed. At this time, the vast majority of the elements in the universe are hydrogen, accounting for 75%. The rest is almost helium, and the other elements account for very little, even less than 1%.

Even in today’s universe, the proportion of hydrogen and helium is still up to 99%. Stars are the earliest objects in the early universe, so the main material of stars is hydrogen, followed by helium. In fact, the celestial bodies composed of hydrogen and helium are very common in the universe. For example, the gaseous planets such as Jupiter and Saturn in the solar system are mainly composed of hydrogen and helium.

Stars are different from these gaseous planets in that they have more mass. When the mass reaches a certain degree, ordinary celestial bodies will become burning stars. And all these factors have a huge relationship with gravity. Everything in the universe is formed under the action of gravity.


Gravity is the real controller behind the universe. When the mass of the sun increases, its gravity will also increase. When it reaches a critical point, gravity will continue to squeeze itself, and the temperature of the sun’s core will become higher and higher, reaching the temperature of nuclear fusion reaction. So the sun’s core was activated and ignited, becoming a continuously operating controllable nuclear reactor.

As a matter of fact, the gas giant planets like Jupiter have solid hydrogen in their cores, which is squeezed by hydrogen under the action of gravity. However, its mass can not reach the level of igniting laser internal fusion, so it can only exist as gas giant planets.


Nuclear fusion is a very special combustion mode. It uses chemical reactions at the atomic level, which is completely different from ordinary material combustion. Therefore, the combustion of nuclear fusion does not need oxygen and other combustion supporting gases, only needs enough hydrogen and other combustion, and can continue to burn.

Because the mass of the sun is 330000 times that of the earth, accounting for 99.86% of the mass of the whole solar system, the sun has abundant hydrogen and helium elements. Only enough hydrogen elements can keep the sun burning for 5 billion years, and it can continue to burn for about 5 billion years in the future.

Of course, nothing is endless. Although the hydrogen element of the sun is very abundant, it will be consumed one day. After the hydrogen fuel of the sun is consumed, the life of the sun will come to an end. However, the depletion of hydrogen does not mean that the sun will be extinguished soon, but that it will continue to burn for tens of millions of years.


The nuclear fusion reaction inside the sun is a complex process. The nuclear fusion continuously consumes hydrogen to convert into helium. When the hydrogen is consumed, the hydrogen helium fusion will end. At this time, the nuclear fusion reaction will not stop, but will continue to take place with helium as fuel and transfer to other heavy elements.

In this process, the sun will become unstable, and the surrounding material will begin to expand and become a red giant. When the helium fusion is over, the sun will enter the final stage, and the outer material will leave behind, leaving the inner core evolving into a white dwarf. The separated matter around the sun contains a lot of heavy elements, which is one of the sources of heavy elements in the universe.


This shows how important stars are for the evolution of the universe. In addition to being an important energy celestial body, they are also an important chemical plant for element evolution. They can continuously evolve primitive elements such as hydrogen and helium into various heavy elements to enrich the elemental matter of the universe. With abundant heavy elements, other events can evolve, such as the birth of life.

Stars have their own life cycle, from tens of millions of years to tens of billions of years. The end of the sun in 5 billion years also means the end of the entire solar system. At that time, if the earth wants to be alone, there is no other way out except to leave the solar system. If we stay in the solar system, the fate of the earth can only be destroyed and completely disappeared in the universe.

To let the earth leave the solar system freely, we need a very strong technological force. Fortunately, the time left by the sun is still very long, billions of years, enough for human beings to develop to the advanced stage of civilization. At that time, human steps may have spread all over the universe.

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