Shrinking Sun

Actually I think that the loss of mass the sun suffers will make it increase in size. The star is essentially a ball of gas which shrinks due to its large gravitiational field. The gas heats up and eventually 'ignites' and a fusion reaction begins. The increased temperature increases the pressure, and eventually the shrinking due to gravity is balanced by the pressure due to temperature. Thus, as the mass decreases when the energy is released the gravitational field decreases, and the pressure starts winning the battle, resulting in a red giant. Obviously this isn't the case in every star, it depends on the initial mass. It is the fate that awaits our star though, IIRC.

I think I may have had a badly worded post (coupled with being tired and not thinking straight). My point was meant to be that a loss of mass will cause the sun the increase in size due to the pressure, rather than decrease. Not that it would increase by red dwarf proportions. In it's normal state the gravitational forces cause the star to shrink and the thermal pressure cause it to grow. I would imagine that is why the sun oscilates in size, the gravity causes it to shrink, increases the pressure and then the pressure causes it to grow, decreasing the pressure.This message has been edited by happy_atheist, 10-29-2005 02:10 PM