Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Ellingson, Kenneth L on 19/10/2008 13:03:39

Title: Why does the sun take so long to burn out?
Post by: Ellingson, Kenneth L on 19/10/2008 13:03:39

Ellingson, Kenneth L  asked the Naked Scientists:

Why does the sun take so long to burn out?

Knute Ellingson, Chicago

What do you think?

Title: Why does the sun take so long to burn out?
Post by: Soul Surfer on 19/10/2008 13:55:56

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.

Title: Why does the sun take so long to burn out?
Post by: lightarrow on 19/10/2008 14:38:52

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!)

Title: Why does the sun take so long to burn out?
Post by: syhprum on 19/10/2008 15:48:30

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

Title: Why does the sun take so long to burn out?
Post by: lyner on 19/10/2008 18:23:05

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.
http://www.maris.com/content/applets/05_StarLifeTime.html (http://www.maris.com/content/applets/05_StarLifeTime.html) shows an animated life for a number of different star masses.

Title: None
Post by: Jez Ippolito. on 14/03/2011 07:46:01

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...