**10,000 Fans Incentive Program If you're worried about when the sun will die, don't be afraid: that moment is billions of years away.
The sun powers life on Earth, and without this star, we wouldn't be here. But even stars have a finite lifespan, and one day our sun will die.
You don't need to worry about this solar death, though. Like all stars, a churning fusion engine fuels the sun, and it still has a lot of fuel – about 5 billion years worth of fuel.
The sun will begin to die in about 5 billion years, when it will run out of hydrogen.
The Sun will end its life as a white dwarf. As a white dwarf, it is essentially a dead star that has exhausted all the nuclear fuel it is capable of burning. As a white dwarf, it slowly cools and fades away, getting cooler and cooler. This is the final state of low-mass stars, including the Sun.
Although the Sun is a million times the size of Earth, a white dwarf is about the size of our Earth. Most white dwarfs will consist of a special state of ultradense matter called electron degenerate matter. It is a state in which all electrons are in a state of lowest energy.
As a white dwarf, the core of our Sun is mostly composed of carbon and oxygen, which are remnants of burning helium. Around this core there will be a thin layer of helium, which will be the remnants of helium combustion. The outer layer will contain a thin layer of unburned hydrogen. Some white dwarfs do not have this outer hydrogen layer because the thermonuclear combustion of hydrogen during evolution is complete.
When the sun dies, the Earth may not even exist. The sun is slowly expanding. In about 5 billion years, the Sun will enter the red giant phase. At this stage, the sun transitions from burning hydrogen in the core to burning hydrogen around the core, and hydrogen is converted to helium by hydrogen combustion.
Energy production increases dramatically, forcing stars to expand more than 200 times to reach a new equilibrium state. Theoretical modelling and observations, enhanced by distance determination of the Gaia spacecraft, suggest that the Sun is likely to engulf the Earth when it reaches its maximum size.
At some point when the Sun reaches the tip of AGB (Asymptotic Giant Branch), helium combustion will begin. In stars like the Sun, helium burning occurs through heat pulses. In each pulse, the Sun experiences a significant loss of mass.
However, the sun has been experiencing mass loss throughout its life cycle. In the current sun, this rate of mass loss is quite low, as evidenced by the solar wind.
Even now, the earth is losing water. Interactions with ultraviolet radiation fields and particles in the solar wind that reach the Earth are dissociating water in our upper atmosphere. Light hydrogen, in particular, can escape the gravitational pull of the Earth. Observations from previous space missions and the Hubble Space Telescope have shown extensive expanding hydrogen clouds (exosphere) around the Earth. It is estimated that the Earth will lose most of its water within a billion years and is much like Mars. Even if the Sun does not engulf the Earth, the increased luminosity and intense stellar winds in the later stages of its evolution will strip or boil up any remaining atmosphere or oceans. If Earth could survive, it would be a rocky cinder orbiting a white dwarf.
The big question is, "what happens to the gas giants in the outer solar system"? In the later stages of the Sun's evolution, the increase in mass loss will certainly strip the outer atmospheres of Jupiter, Saturn, Uranus, and Neptune; Without detailed calculations, it is difficult to say to what extent.
Again, it depends on the actual mass ejections that occur later in the star.
Rapid mass loss phases of evolutionary and hot pre-white dwarfs. Blazing former white dwarfs, which remain after ejections during the stellar envelope and planetary nebulae phases, have a core temperature of 100,000 K or more and winds of more than 2000 km/s. Then again, will any of these gas giants survive? If they do, they will only be ghosts they once were.
The material ejected from the normally evolved and ejected planetary nebula will enrich the interstellar medium with heavy elements produced by the combustion process of hydrogen and helium. This will produce carbon, nitrogen, and oxygen, as well as process elements like Ba, Zr, and La, among others.
This material-rich cloud combines with clouds of other stars to form dense clouds that may then collapse to form the next generation of stars.
A chart showing the balance between fusion and gravity in a star. （*nasa）
Stars like the Sun are formed when huge clouds of gas, mostly hydrogen and helium, become so large that it collapses under its own weight. The pressure in the center of the collapsed gas is so high that the heat reaches unimaginable levels, and the temperature is so high that the hydrogen atom loses its electrons.
These exposed hydrogen atoms then fuse into helium atoms, a reaction that releases enough energy to defy the strong pressure of gravity and cause the gas cloud to collapse. The struggle between gravitational and fusion reaction energy fuels our Sun and billions of other stars in and around the Milky Way.
But in about 5 billion years, the sun will run out of hydrogen. Our star is currently in the most stable phase of its life cycle, about 4.5 billion years ago since the formation of the solar system. Once all the hydrogen is used up, the sun grows out of this stable phase.
Since there is no hydrogen in the core to fuse, the outer shell of fusion hydrogen will form around the helium-filled core, astrophysicist Jillian Scutder wrote in an article in The Conversation. Gravity will take over, compressing the core and allowing the rest of the Sun to expand.
Our star will become bigger than we thought – so big that it will surround the inner planets, including Earth. At that point, the Sun will be a red giant star that will remain there for about a billion years.
Then, the hydrogen in the outer nucleus will be depleted, leaving behind a large amount of helium. This element will then fuse into heavier elements like oxygen and carbon, in a reaction that does not release as much energy. Once all the helium is gone, gravity takes over and the Sun shrinks into a white dwarf. All the external matter will dissipate, leaving behind a planetary nebula.
When a star dies, it spews a lot of gas and dust into space – called its cladding. The envelope can reach half the mass of a star," Albert Zijlstra, an astronomer at the University of Manchester in the United Kingdom, said in a statement. "This reveals the core of the star, which at this point in stellar life, is running out of fuel, eventually shutting down and eventually dying.
Astronomers estimate that the sun is about 7 billion to 8 billion years before it erupts and dies. Either way, by then, humanity will most likely be long gone.
Our Sun is not massive enough to cause a star** at the time of death, called a supernova, and it will never become a black hole.
In order to produce a supernova, a star needs about 10 times the mass of the Sun. After that, an object of this size forms a dense stellar corpse called a neutron star.
To leave a black hole, a supernova must occur in a star with a mass of about 20 times that of the Sun.