Kenneth, Chicago asked:
Why does the sun take so long to burn out?
Steve - The sunís doing fusion very slowly. It doesnít have to do it any faster to keep itself held up. If the sun did fusion faster it would expand and then the fusion would go slower and it would contract back down again. If the sun was doing fusion too slowly it would contract until the fusion got fast enough to hold it up. The sun is just self-regulating and thatís why itís going to last 5 billion years.
Ellingson, Kenneth L asked the Naked Scientists: Why does the sun take so long to burn out? Knute Ellingson, Chicago What do you think? Ellingson, Kenneth L , Sun, 19th Oct 2008
The sun is a moderately sized star and the smaller the star the longer they last. Stars with masses more than ten times the sun are vastly brighter and burn out in a few million years. As it has taken four thousand million years for life as we know it to evolve intelligence it sa good time we are on a reasonably long lived dtar that is about half way through it's lfe or we would have been fried by the death throes millions of years ago. Soul Surfer, Sun, 19th Oct 2008
The nuclear reactions require extremely high densities and temperatures to happen; in our star these conditions are quite satisfied, but not very well. For this reason the reaction's speed is low. For that reason we are still struggling to reproduce such reactions in laboratory (the hope of energy gratis for everyone!) lightarrow, Sun, 19th Oct 2008
I believe that the the rate that nuclear processes proceed depends on the ratio of the four fundamental forces in 'nature' to each other but it needs a fully fledged nuclear physicist to explain in detail syhprum, Sun, 19th Oct 2008
Very big stars - many Solar masses - will only last for a few million years because the internal pressures are so high, the reactions happen very much quicker.
Even my best yule log burns for only two hours, if I'm lucky, so whoever made our star, had the best kept secrets to fire for a good few years, just until the three wise men came along that is. Silent night... Jez Ippolito., Mon, 14th Mar 2011