I'm being picky here, but the word "proven" doesn't really make sense in the context. A more accurate way of expressing the title would be "Evidence supports a different theory" or "Less support for this theory", as theories can never be proven.
My understanding of the theory is that Theia hit the earth, that most of it was absorbed into the earth's surface/ molten core, and that the rest, along with some of the earth was ejected out into space.<p>If that's the case I don't see how there is any way of 'proving' that the isotopic signatures we are matching with those of the moon are 'native' and not already part of some Earth/Theia mix - in which case they'd match with a Moon that was already part of an Earth/Theia mix. Without knowing the composition of the earth 4.5 billion years ago, I'm not sure you can say otherwise?
I don't understand. If "theia" hit earth and formed moon, why would the istopic signatures be any different. Now both earth and moon come from same pair of different objects.
I think we should remember the vast differences between reporting about scientific papers and the peer-reviewed papers themselves; I have a good feeling, based on previous experience, that most of the caveats raised here will be tackled by the paper, whose tone will probably be less decisive.
One thing I've never understood about this model: according to orbital mechanics, you can't "boost" yourself into an orbit that doesn't include the point you're already in. So if the mass that became the moon started at the surface of the earth, its orbit would just smash it back into the earth again. You can see what I mean here: <a href="http://isthis4real.com/orbit.xml" rel="nofollow">http://isthis4real.com/orbit.xml</a>
The theory was merely proven to be theoretically falsifiable, and not incorrect. They clearly state in the article that they couldn't find any proof of two parents, which for the moment points to the moon having only one parent. This contradicts the previous theory, but doesn't make it false.