(ORDO NEWS) — You don’t have to worry about the death of the Sun anytime soon. Like all stars, the Sun has a fusion engine to power it, and it still has a lot of fuel left, enough to last about 5 billion years. But when a star begins to die, how will that happen?
Humanity may not catch the death of the Sun, but when it happens, how will it be? We understand the processes occurring inside our star.
Stars like our Sun form when a huge cloud of gas (mostly hydrogen and helium) becomes so large that it begins to collapse under its own weight.
The pressure at the center of this collapsing mass of gas is so great that the atoms there begin to approach within a very short distance, and the temperature is so high that the hydrogen atoms begin to lose their electrons.
These bare hydrogen atoms then fuse into helium atoms, and this reaction releases enough energy to resist the force of gravity destroying the cloud of gas. The battle between gravity and fusion energy powers our Sun, as well as billions of other stars in the galaxy and beyond.
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 and has been there since the formation of our solar system, about 4.5 billion years ago. Once all the hydrogen has been used up, the Sun will exit this stable phase.
If there is no hydrogen left in the center of the star, then a shell of thermonuclear hydrogen will form around the helium-filled core.
Gravitational forces will take over and compress the core, allowing the rest of the Sun to expand. Our star will become larger than we can imagine – so big that it will envelop the inner planets, including the Earth. That’s when the Sun will become a red giant, which it will remain for about a billion years.
The hydrogen in this outer core will then be depleted, leaving only a helium core. This element will then fuse with heavier elements such as oxygen and carbon in reactions that no longer generate as much energy.
Once all the helium is gone, gravity will take over and the sun will turn into a white dwarf. All of the outer material will dissipate, leaving behind a planetary nebula.
Astronomers have calculated that the Sun is 7 to 8 billion years away from such a death. One way or another, humanity by that time may have long since disappeared or moved to other planets.
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