Question: The Life Span of the sun is estimated to be billions of years, but since the world was created a long time ago by what is believed as a big bang, Does it mean after those billions of years, The sun will go and the life will come to an end?

Isabel Webb answered on 19 Mar 2014:

Stars all go through the same life cycle. Just like we go from baby, to child, to teenager, to adult, to elderly person, to death, so do stars have a life cycle.

They start as a NEBULA – a huge dense ball of dust and rocks and gas.
They then start to heat up and release light. Eventually, they become a star like our sun – which is a main sequence star. A star the size of our sun lives for 10 billion years. The Earth is 4.5 billion years old at the moment, so we aren’t even half way through this stage yet.
After all of the hydrogen in the star is used up for energy, it begins to cool, and grows in size massively. It is now called a RED GIANT, and is full of helium gas. When our sun becomes a red giant, it might be big enough to swallow earth up! When our sun forms a red giant, life will come to an end!
After all the helium is gone, it loses its outer shell and starts to shrink. It becomes a WHITE DWARF.
Once the star cools so much it stops shining it becomes a BLACK DWARF, and at this point, it stays like this forever.

Really big stars (10x size of our sun) have a different life cycle.
Instead of a red giant, they form a RED SUPERGIANT.
When the helium runs out, the supergiant centre collapses, causing a huge explosion, called a SUPERNOVA. The supernova shines brighter than its entire galaxy at this point!
After the supernova, if there is enough matter left over, it will shrink to form a BLACK HOLE. Black holes are so dense they draw all other matter around them into them by their huge gravitational force.