[Elliott Birrell]

Elliott Birrell  asked the Naked Scientists:
   
I was wondering how is it possible to breathe and live on our planet, where do all the gasses come from? Also how are they able to stay inside our planet and not on other planets in the solar system?

What do you think?

[Stefanb]

I believe that the common conception is that all the meteorites that pounded into the earth kept some of their ice back in the days of formation. Then the molten material of earth melted the ice and vaporized the water. However, Earth's gravity held the water vapor in. After millions of years, enough water vapor had built up to actually have rain. This rain helped cool off Earth in its molten state. Much of the material that pounded into earth reacted and released Methane, Carbon Dioxide, Nitrogen and other minor gasses. Eventually, autotrophs formed and took the Carbon Dioxide and used it, sunlight, and water, to make Oxygen. After much was built up, heterotrophs later formed which ate other organisms. Yay! Please correct me if I'm wrong  []

[Karen W.]

What a terrific question!!!

I have often wondered that!

Stephan Great explanation. Is that therory or conjecture based on the deduction about how gases etc are formed and how long it would take for these things to build up around the earth?

So I assume this would have happened after the big bang eh... you know..the meteors etc....?

Fascinating!

[Karen W.]

If the Heterotrophs ate other organisms ....where did the other organisms come from? Does'nt that imply there was already life on earth in the form of these other organisms?

[LeeE]

Of the planets, only Mercury has no atmosphere.  I believe Pluto has no atmosphere, but it's no longer regarded as a planet.  Even some of the larger moons have an appreciable atmosphere.