As others said, it was actually a protoplanet the size of Mars, according to the impact theory, that created the Moon, but it's much the same difference as far as this question is concerned.
We don't know. Life started very early on possibly within a few hundred million years of the impact. It could have
This might mean that life evolved in complexity far more rapidly in the early stages. Or it might mean that it evolved around another star.
There may be other scenarios as well.
The impact that formed the Moon happened quite late in the solar system and Earth was probably already habitable before the impact, also Mars and the protoplanets also. Though it would have had so many impacts that early life might have arisen and gone extinct many times over. So all those options are possible.
So it's also possible that life arose before the impact but the impact made it extinct.
It depends for instance on how hardy this very early life was. Could it survive an impact, and being thrown off into space and then returning on a rock to reseed the planet it evolved on?
Perhaps it's not impossible that we find evidence of this eventually? The impacts must have sent debris all over the solar system, maybe we'll find evidence on other planets or asteroids that we can trace back to the Moon forming impact or even before?
We don't know. Life started very early on possibly within a few hundred million years of the impact. It could have
- Come to Earth from Mars
- Developed very rapidly on Earth itself - if so it suggests life evolves very readily to the early stages of the first living cells and may perhaps be widely prevalent in the galaxy (it is a big extrapolation from one instance - but the thing is to have intelligent life right now requires all the stages to go through quickly but doesn't require the first stage of the earliest life forms to happen so very quickly as that, if it had taken a billion years it would hardly have made much difference really, so you can't argue it from the anthopic principle)
- Evolved on Earth before the impact that created the Moon.
- Evolved on the protoplanet that impacted with Earth
- Evolved at an earlier stage in the planet embryos - maybe life evolved right early on - in the early solar system then asteroids like Ceres etc had liquid water, is thought. Perhaps right back then early Ceres like planet embryos had liquid water in them and life evolved there
- Evolved on a planet around another star. The star happened to pass through our solar system early on. Either the condensing gas cloud, or later on when it was full of debris and impacts brought life from the other star to Earth
This might mean that life evolved in complexity far more rapidly in the early stages. Or it might mean that it evolved around another star.
There may be other scenarios as well.
The impact that formed the Moon happened quite late in the solar system and Earth was probably already habitable before the impact, also Mars and the protoplanets also. Though it would have had so many impacts that early life might have arisen and gone extinct many times over. So all those options are possible.
So it's also possible that life arose before the impact but the impact made it extinct.
It depends for instance on how hardy this very early life was. Could it survive an impact, and being thrown off into space and then returning on a rock to reseed the planet it evolved on?
Perhaps it's not impossible that we find evidence of this eventually? The impacts must have sent debris all over the solar system, maybe we'll find evidence on other planets or asteroids that we can trace back to the Moon forming impact or even before?
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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