How can we even think about the sun in this way? Won’t the sun last forever? The reason science can consider this question is that we know the sun is simply a star, and this means we can compare it with other stars. And since other stars have gone through a process of change, science believes that the same will eventually happen to the sun.
At one time, in fact, it was believed that the sun was a body that was slowly cooling off. It was simply “burning”. Now we know that if this were so, the sun could only have lasted several thousand years.
If it is not “burning”, then what is going on in the sun? We now have evidence that indicates that the sun’s radiant energy is the result of atomic transformations. The hydrogen atoms in the very hot interior of the sun combine to form helium. This sets free the energy which flows steadily from the inside of the sun to its surface.
How long can this go on? Well, let us suppose it goes on exactly as it is doing now for another 150 billion years. As a result of this process, the mass of the sun would be reduced by roughly I percent! So it seems that the sun can continue to shine and supply the earth with energy for many billions and billions of years to come.
What Year Will The Sun Explode?
In about 5 billion years, the Sun will start to run out of hydrogen in its core to fuse, and it will begin to collapse