• Question: Why do we (on earth) have oxygen, but other planets do not?

    Asked by kittykat1999 to Mike, Pip, Tianfu, Tim, Tom on 29 Jun 2012.
    • Photo: Tim Stephens

      Tim Stephens answered on 29 Jun 2012:

      When life started on earth, bacteria and then plants created oxygen. I don’t know if other planets have no oxygen (it’s pretty likely that they do), but Earth is special because it’s just the right distance from the sun to get enough heat to have liquid water on the surface. That’s what made life possible here.

    • Photo: Tom Lister

      Tom Lister answered on 30 Jun 2012:

      As Tim said earlier in the week, oxygen was made in the stars. It was released from the water to help create our atmosphere, which I’m not sure has happened in the same way anywhere else we know of. Other planets are bound to have oxygen though – for example there is lots of frozen water (H2O) on one of Saturn or Jupiter’s moons (can’t remember which), plus evidence of water previously on Mars.

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