Newborn moon may have had many mini-siblings in Earth orbit long ago

[Admin]

When Earth and our moon were much closer together than they are now, the duo could have had tiny companions, or a disk revolving around them in orbits around the pair's poles, a new study finds.

Newborn moon may have had many mini-siblings in Earth orbit long ago : Read more

 

[ChrisA]

Is it really so surprising that after a huge off-center collision with a Mars-size planet, there were many chunks of debris flying in many different directions and not just one round spherical chuck?

Common sense suggests the bits of hot and vaporized debris scatter just about everywhere, some would escape the Earth; 's orbit and fall into the sun some would fall back to Earth and millions of bits would be in different orbits around Earth.

Either this new study has discovered the obvious or (more likely) it discovered something the author of this article did not report on. Likey what's missing is the mechanism for the debris cloud to condense into multiple large bodies, and what happened to those large bodies. THAT would be interesting to know.

 

[Torbjorn Larsson]

However, previous research suggested that when the moon was born, its orbit was inclined by at least 10 degrees.

Those are rather old results, heavily relying on massive analytical models before doing simulations (for the youngest paper), remarkably robust against mistakes since the last paper find some in the earlier work. But I would feel much more comfortable if it could be redone in general gravitational system simulations such as the new particle simulations here.

Coincidentally, on the particle level the equatorial orbits are stable, which makes you wonder what mechanism in the analytical models would prevent that. Alas, those models were the result of a huge task, and while they compare e.g. tidal models I don't see any sensitivity analysis of the various basic model parts meaning the resulting model inclination appears unexplained.