A new Moon creation theory

[JamesF]

The Moon may not have been created as a result of another body colliding with the Earth, allegedly:

http://www.bbc.co.uk/news/science-environment-19992233

James

[Capricorn]

What is different?

Something impacted the earth, material was thrown off.

Only difference is the rate of spin of the earth at impact, which having been impacted by a large body would more then likely have had its rotational velocity changed afterwards.

Still seems basically the same to me.

[JamesF]

I didn't word that very well at all. I meant the Moon might not have been (largely) the other colliding body.

What they seem to be suggesting is that the colliding body became part of the Earth and that debris thrown out from the Earth became the Moon. I think it's interesting that some scientists still feel the subject is open to debate. When other threads are discussing what might have been going on before the Big Bang I guess it's a timely reminder that there's an awful lot closer to home that we may not actually be that sure about yet.

James

[LukeSkywatcher]

It has long been thought that the lunar body resulted from an impact between the early Earth and another planet-sized object 4.5 billion years ago.

But this theory predicts Earth and its satellite should have a quite different chemical make-up - and the data shows in fact they are very similar.

Scuse my ignorance (maybe i am reading this wrong),but the theory of the Moon being formed after a collision between Earth and another body surely means that both the Earth and the Moon should have a similar chemical make-up (as they do).

If the Moon had a very different chemical make-up to the earth, then it would suggest that that the Moon was not created from a collision between Earth and another body.

Hope this makes sense.

[LukeSkywatcher]

I didn't word that very well at all. I meant the Moon might not have been (largely) the other colliding body.

The Moon was not the other colliding body. The colliding body was something about the size of Mars. Before the collision, the Moon did not exist. The material thrown off from the collision led to the formation of the Moon. So the Moon is basically made up of the same material as the early earth. Thats why the chemical make-up of the Earth and Moon are similar.

Its a pretty solid and extremely widely accepted theory.

[JamesF]

My understanding was that a large proportion of the material forming the Moon was thought to have come from the impacting body. This article appears to suggest that has been the view for some time. The new idea appears to be that the material forming the moon mostly came from the material forming Earth rather than the impacting body.

I'm beginning to doubt my own comprehension now though.

James

[LukeSkywatcher]

My understanding was that a large proportion of the material forming the Moon was thought to have come from the impacting body. This article appears to suggest that has been the view for some time. The new idea appears to be that the material forming the moon mostly came from the material forming Earth rather than the impacting body.

I'm beginning to doubt my own comprehension now though.

James

I'm sure some of the chemical make-up of the Moon came from the body that collided with Earth and also from the Earth itself. Its a bit like panetary DNA.........some genes from the mother and some from the father.

Largely though the chemical make-up of the Moon is similar to earth with a bit of chemical make-up from the colliding body...........whatever that was.

[sologuitarist61]

I read that to mean that everyone stills thinks the moon was the result of an impact with earth, but that they are just giving other reasons why the Earth and Moon are so similar

There is another reason why the chemical make up is so similar and that is if the colliding body was also formed in new Earth orbit - then it to would have been made from the same stuff surely?

[Naemeth]

In essence, it's not that new. The theory is still largely the same as it was in the 70s when William Hartman proposed it (or convinced the scientific community, something like that ), except we now believe the moon was created from ejecta from the early Earth, not the impactor (roughly the size of Mars), which makes sense certainly, as chemically the Earth and Moon are very similar, and could only be formed in the same part of the solar system.