Philopophy Of The Cosmos - Diminishing Sun
My understanding of the sun is that at the core, nuclear fusion occurs. When this happens, two hydrogen atoms are made to become one helium atom. The wieght of the one helium is less than that of two hydrogens. This mass is converted into energy, mainly in the form of light and heat, which makes the sun shine. The mass of the sun should be decreasing due to this. This should also mean that its gravitational pull should also desrease. My question is that over time, does this mean that the suns gravity will no longer be sufficent to hold the planets in orbit? Or is the mass loss so small it is negligible?
Ben (u 4868271)
[[black I have a blurry idea about this, but I think because E = mc^2, and the speed of light is very large, so the change in mass is very small- if not the sun would shrink much too quickly. I would also like to know more about this though.
Ly (u 4677579) ]]
That's right, Ly. The sun's mass IS diminishing, but it will die from other causes long before it loses enough mass to make much difference to the planets' orbits.
while reading this post i was reminded by another thought i had had a while ago. I was wondering if more hydrogen atoms are being produced all the timem and if not, how is there enough to produce all of the stars all of the time??
Hoping someone can clear this up for me :)
Good question. Inside galaxies, there's a LOT of left-over hydrogen from stars that have exploded. So that's where new stars come from. It's also possible that new hydrogen is being created from scratch, but that theory is very out of fashion these days. Dayal will talk about that theory later.
Is it possible to split the helium atoms into two hydrogen atoms if the energy given off during nuclear fusion (ie: heat and light) is somehow reclaimed?
Tim (u 4311243)
Yup. I don't know any way to do it on a large scale, though.
A Note: I believe the Sun's mass will eventually decrease such that it's gravity will alter its very size. With less mass the gases of which it is constituted will not be attracted as at present and the size of the sun will increase to such a point that it will indeed consume us… And this will happen before the estimated 4billion-year-from-now death of our Sun. Correct anything if wrong please Jason.
Daniel (u 4587729)
Daniel, yes, it's certainly true that the Sun is going to get bigger and consume the Earth. (Funnily enough, it won't initially heat the Earth up very much even when it gets so big that we're inside it, because by that time it will be very very diffuse, but it will eventually vapourise us.) It's also true that its mass is decreasing. I'm not sure exactly how closely those two things are linked. There are other important factors in the expansion, like the changing nuclear reactions (of which there are many, not just hydrogen —> helium). Let's ask Dayal for details.