Moon formation: Was it a 'hit and run' accident? (Earth, Venus, Mars)

[Baldrick]

Just had a read of this online and found it interesting.

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

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.

[Glitch]

Additionally, without the Thea impact the nickel-iron core of Earth would be about two-thirds its current size, and the Earth would have cooled much quicker than it has. Thea would have had to be larger than the moon, but smaller than Venus. Which is why I think most consider Thea to have been roughly about the size of Mars.