Moon formation: Was it a 'hit and run' accident?

[dipsydoodle]

Scientists have proposed a fresh idea in the long-running debate about how the Moon was formed.

What is certain is that some sort of impact from another body freed material from the young Earth and the resulting debris coalesced into today's Moon.

But the exact details of the impactor's size and speed have remained debatable.

In a report online to be published in Icarus, researchers suggest that the crash happened with a much larger, faster body than previously thought.

http://www.bbc.co.uk/news/science-environment-19011013

[htuttle]

1. One obvious question is, "then where did it go?"

It seems unlikely that an object could maintain solar system exit velocity after a collision with the proto-Earth. So I'd presume that the colliding planet eventually started orbiting the sun.

Was it Mars? Did it disintegrate into asteroids? (if that's possible). Did chance and gravity wells fling it out of the solar system after all?

Seems like one advantage of the current Theia theory is that there's nothing left over to account for.

[Posteritatis]

2. A lot of orbits aren't stable, and the early solar system was incredibly messy

If something like that hit a glancing blow against Earth (and didn't smoke it completely like the current theory suggests) that already means it's in a weird orbit anyway. If it happened that way, the thing's probably sitting inside one of the gas giants or the sun.

[Odin2005]

3. Theia was in one of Earth's Langrarian points.

But such orbits are only stable for a few million years.

Most of Theia, including all of it's iron core, was absorbed into the earth. bits of the mantles of Earth and Theia consolidated into the Moon.

[Glassunion]

4. It eventually stabilized its orbit and

is now the governor of New Jersey.