This might sound a little sad, but our sun will eventually die. Don't
get worried though, it won't happen for another 5 billion years or so.
With any star, they have a lot of fuel. This fuel is an element
called hydrogen. After a very very very very long time (10 billion or
so years our sun), it will run out of hydrogen. After the sun uses the
hydrogen, that fuel becomes helium or some other light element. Once
the hydrogen is gone, the helium will fuse into bigger elements. At
that point, the star grows to big very big. In fact, the Earth will be
swallowed up by our sun when it becomes a Red Giant. Then it will
collapse and cool down.
Remember, 5 billion years is a very long time before the sun dies.
It's been almost that long since it first gave off light. You won't
have to worry about it dieing any time soon.
Adam
(published on 10/22/2007)