Hydrogen Gas

What with all the immense clouds of hydrogen revolving around in the universe, what keeps them from blowing up like the Hindenberg Blimp? I’m guessing it is lack of oxygen.

And you would be right. I doubt there are significantly large amounts of oxygen gas anywhere in the universe, other than that produced by living organisms. O[sub]2[/sub] is very reactive with a number of other compounds, and it doesn’t last long unless it is continously replenished. IIRC the majority of oxygen in the universe is locked up in water and cannot react further with hydrogen.

And what about those immense accumulations of hydrogen gas called stars. Why are they so inert?:stuck_out_tongue:

Well, in all seriousness, stars aren’t “blowing up” in the traditional combustion sense; they release energy from fusion.

Stars walk a balance between gravity and their own explosions. Gravity is what makes them spheres, their own explosions keep them from collapsing entirely. Of course, when the main sequence is done and the main fuel source is exhausted, the higher-energy sources are consumed, breaking the balance and leading to an explosion, either a nova or a supernova depending on size. Then, when that’s over, the fuel is nearly all gone, so the star collapses. Now, if the star has enough mass nothing keeps it from collapsing to a point called a black hole. So it does. But our sun won’t go that route: It isn’t that large. About four billion years from now, our sun will undergo a nova and eat up all the planets from Mercury to Mars. This includes Earth, unless us humans have moved it by then. Then it will eventually collapse to a white dwarf (I think), a relatively cool, relatively small, very compressed star. Such is the life of an average class-G star.

Almost. As I understand it ( this understanding only comes from a book on Stephen Hawking- I haven’t looked extensively into this) It’s not the fusion ‘explosions’, H-bomb-style that keep the star from spontaneously collapsing. It’s the energy (sort of a wavicle thing)pressure of the energy relesed by the fusion (kind of like intense solar wind), which in turn is caused by the intense pressures on the H atoms caused by gravity acting on the star’s own mass- it’s beautiful.

Like any man-made machine, the star is inefficient. It uses fuel and causes a lot of heat (~aka entropy).

“also known as” entropy?

‘like any man-made machine’

I realize what you’re saying, but the concept of man-made stars struck me as intensely odd. I can just imagine it: This sunny day brought to you by Coca-Cola. Or: Don’t forget to pay your sunlight tax, or we’ll toss you down a salt mine.


There was a Doctor Who episode about man having created suns out by Pluto to light it, and then charging horrendous taxes to the workers for this sunlight!

don willard - - another thing to keep in mind is that those nebulae of hydrogen are not thick clouds…they’re actually so sparce that they would pass for a vacuum in one of our labs. They look thick in photos because you’re seeing something that is trillions of miles wide compressed down into a small image.

Our sun will not go ‘nova’. A nova is when one of the stars in a binary system accretes enough new mass from its companion star and suddenly flares up. Of course, our sun is not part of a binary system. Our sun will expand (engulfing Mercury & Venus as you noted…and maybe Earth) and then contract back down into a white dwarf. During & after the contraction, it will form a nice ‘planetary nebula’ (nothing to do with planets…just a bad name).