> The Moon may have been formed by a collision between Earth and an object that was strikingly similar in composition to our own planet. This could help resolve why Earth and Moon rocks are much more similar than we would expect from this “giant impact hypothesis”.
Unnecessary IMHO. First, there are significant differences between Moon rocks and Earth rocks. A major one being the much lower incidence of hydrogen in moon rocks. Another major one being the large difference in bulk density between the Earth and the Moon indicating that the Moon has much less iron. The ancient surface of the Earth would have come from the same material as the Moon, the result of the downfall of much more than the Moon’s mass of rocks onto the proto-Earth after the impact.
> the models indicated a 20% chance that the impact could have been between such similar proto-planets.
I’m not surprised, but it’s nice to see an actual percentage.
> Even if, as the French-Israeli study now suggests, the Earth and Moon got started from very similar building blocks, this bombardment should have had a much bigger effect on the bulkier, heavier Earth with its much stronger gravity, shifting the balance of its ingredients away from that of the Moon. The small, but significant, difference in the tungsten isotopic composition between Earth and the Moon perfectly
corresponds to the different amounts of material gathered by Earth and the moon post-impact.
Good point. The technical and common name for this is “late heavy bombardment”. Can we estimate the total mass of the “late heavy bombardment” from this?