Science a GoGo's Home Page Forums General Discussion Physics Forum Idea on the Sun

Hey everyone. I got into a diccussion with a close friend of mine. He put up the idea that planets are possibly fueling the Sun.

The Sun runs on hydrogen, and the Sun is hydrogen. Looking at that, the question came. Where does the Sun get its fuel? My friend says that the planets are fueling it. Running into it, colliding with other objects in space, meteors, comets, etc. I'd also heard a rumor that the sun was getting bigger, with a possiblity of "eating" other planets. More evidence. What do you guys thing of this?

The Sun is mostly hydrogen. It is a LOT of hydrogen. It's so much hydrogen that it will take millions and probably billions of years to use all of it. It doesn't need any energy from the planets, which altogether constitute far less mass than the sun by itself.

Eventually, when the sun begins to run out of fuel, it is speculated that it will grow in size so much that its radius will be larger than the orbit of many of the planets.

The amount of hydrogen in all of the planets combined is such a small fraction of the mass of the sun that they are of no consequence. And given their mass is not decreasing by any measurable fraction one can absolutely rule out the possibility.

Your friend sounds like someone that would benefit from starting to read Astronomy Magazine or Scientific American. You might suggest it to them.

Thinker, here's some concise info to be getting on with:

'The Life Cycle of a Sun-Like Star'
http://wind.caspercollege.edu/~marquard/astronomy/sunlike.htm

No I don't think the Sun is getting bigger....not yet, not for another 5 million years, anyway.
If anything the Sun is getting smaller....since it is burning up Helium at a prodigeous rate.
Temperatures and densities in the center of the Sun are so great that hydrogen nuclei fuse into helium nuclei. The creation of each helium nucleus requires four hydrogen nuclei.
One helium nucleus has 99.3% of the weight of four hydrogen nuclei. This excess of 0.7% of hydrogen mass compared with helium mass .....is converted into energy.
Using Einsteins equation E=mc'2
Then:-the Sun converts 600 million tons of hydrogen into 596 million tons of helium every second. This extra 4 million tons is converted into energy:
Therefore the Sun is losing 4 million Tons every second.
It has done, and will continue to do so until the Hydrogen runs out.

Redewenur posted a nice URL as to what happens next.

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"You will never find a real Human being - even in a mirror." .....Mike Kremer.
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Mike said "No I don't think the Sun is getting bigger....not yet, not for another 5 million years, anyway"

Don't panic, Thinker, he meant '5 billion'.

A couple of quick corrections Mike.

The first that red caught ... that is billions with a "B." The second is that the sun is fusing hydrogen and creating helium. When the old girl moves to the helium cycle we'd best not be here.