Thanks, ciitrusy ^_^
Quote:
wild-witch wrote:
Well, I already know how our Atmosphere was formed.
Gases and whatnot pumped out by the very first volcanoes.
But, what I want to know is how that makes our Atmosphere lighter than Jupiters Atmosphere (Which, if we were to go there, would crush us)? |
Well, that's down to pressure. It's not so much that Jupiter has a heavier atmosphere - in fact, it's mostly hydrogen with a smidgeon of helium, which are the two lightest elements. In contrast, our atmosphere is nitrogen and oxygen (again, with a few other things, like argon, carbon dioxide, water vapour, a tiny bit of methane, stuff like that), which are heavier.
Jupiter's atmosphere would crush us at certain altitudes because there's so MUCH of it. Almost the entire planet is, well, atmosphere, with liquid hydrogen inside and POSSIBLY a rocky core buried waaay down deep. Again, it's down to planetary formation and a large amount of chance - it so happened that there was more gas in the outer parts of our solar system when it was forming, which got picked up by the planets that were being made there and scrunched in to a ball.
The fact that, in this solar system, all of the gaseous planets are on the outside (Jupiter and Saturn are Jovian planets, ie. Mostly hydrogen, and Uranus and Neptune are ice giants, largely hydrogen and helium but also with a lot of ices - water ice, frozen ammonia, frozen methane, stuff like that) and all of the terrestrial (rocky) planets are on the inside is pretty much down to chance. We know of many, MANY other star systems, now, and these systems vary hugely.
There is, for instance, Gliese 581, which has three known planets - all rocky, terrestrial ones. As far as we know, there are just no gas planets there. But something like 55 Cancri has five known planets, the innermost of which is probably a terrestrial 'super-Earth' (with a mass similar to that of Neptune), while the other four are all Jovian gas giants. In the case of 55 Cancri, the four innermost planets are all clustered around in an orbit smaller than that of our own Venus, while the fifth has a similar orbit to Jupiter's. That's a hell of a gap between them!
But yeah - our atmosphere is thinner than Jupiter's pretty much by chance. If there had been large quantities of hydrogen gas around when the inner planets were forming, they might be gas giants with similar atmospheres to Jupiter as well, but as it happened, it was well past us and we ended up with a relatively thin atmosphere.