When will the sun die

Will the sun shine forever?

The sun is a gigantic nuclear fusion reactor. It consists mainly of hydrogen. Inside, the pressure and temperature are so high that hydrogen atoms fuse together to form helium atoms. A tremendous amount of energy is released in the process.

But, as I said, the hydrogen supply is not infinite. After its hydrogen supply is exhausted, the sun puffs up. It will temporarily shine even more intensely: As a "red giant", a giant star, its luminosity will be twice as great at the age of around ten billion years as it is today.

However, it will no longer appear yellow but red because it will be much cooler. In the center all hydrogen has now been used up and a ball of helium remains. The "red giant" will swallow the planets Mercury and Venus and destroy life on our earth. No wonder, because it will be over 1000 degrees here - the oceans will evaporate.

But this stage is also over: At the age of about 13 billion the sun will reach a hundred times the diameter of today and its luminosity will be 2000 times stronger, but then on the surface there will be "only" 4000 degrees Celsius (today: 5500 degrees) .

The final stage is reached when the outer solar envelope is shed and the "red giant" shrinks to a "white dwarf", a super-compacted remnant of stars. The "white dwarf" is a star about the size of the earth, but still half the mass of the sun.

Astronomers observe suns all over the universe. Stars that are just emerging or, like our sun, are "in their prime" or star corpses.

The novas or supernovas, exploding stars, are spectacular. They emit as much energy within a few weeks or months as our sun does in ten to 100 million years. However, our sun is spared this fate, it is not heavy enough to ignite as a supernova. But it is definitely enough to become a "red giant".

Author: Barbara Siemes