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Collision With Earth's "Little Sister" Created the Moon
astroengine writes The primordial planet believed to have smashed into baby Earth, creating a cloud of debris that eventually formed into the moon, was chemically a near-match to Earth, a new study shows. The finding, reported in this week's Nature, helps resolve a long-standing puzzle about why Earth and the moon are nearly twins in terms of composition. Computer models show that most of the material that formed the moon would have come from the shattered impactor, a planetary body referred to as Theia, which should have a slightly different isotopic makeup than Earth.
What about this explanation: a planetoid smashed into early Earth and split Earth into two. The two halves eventually smashed back together, but created the moon in the process. One "half" may have mixed more with the collider than the other due to the angle of impact, creating the slightly different isotopes in the parts of it that became the moon.
Table-ized A.I.
So Gaia banged her little sister and made the moon? I assume rule 34 has already been satisfied for this, right?
Serious? Seriousness is well above my pay grade.
Why should the material composition of Theia have differed all that much from the Proto-Earth? They formed from the same planetary nebula, and at relatively similar distances from the Sun; shouldn't they have been similar in composition? And how can anyone state with any certitude, 4+ billion years later, how much of the merged Earth's crust was from Theia, and how much from the proto-Earth, and whether the lunar material was one, the other, or mostly mixed? It was a long time ago, and the Early Heavy Bombardment period would have stirred things up further. In fact, it's not unlikely that the Early Heavy Bombardment material was long-period debris from the original collision.
If Theia had formed substantially closer, or substantially farther away from the Sun, then the debris from the collision could hardly have remained close enough that the shards would coalesce to form the Moon. The differing orbital velocities would have seen to that.
Our substantial magnetic field may be due to the merging of the iron cores of the Proto-Earth and Theia. Earth is the most dense planet in the solar system, and from what we know of Mars and Venus, we suspect that our iron core is far larger than the other terrestrial planets.
Venus has a super-thick poisonous atmosphere; it's at least possible that our large Moon has, over a period of 4+ billion years, "skimmed away" enough of our atmosphere to have protected the Earth from a similar fate.
Of course, we only think that our atmosphere is right because we evolved here, in this atmosphere; if the atmosphere had been different, we would have evolved differently, and (had intelligent life developed at all) we'd think that THAT was the right sort of atmosphere.
You can call planets planets or call them aardvarks. It makes no difference. The name we give it has no meaning except to the person giving the name. Another person might call it something else. Who can say which is right? You because you give it a name in English, or a first nation's person who named it in their language? Which is correct? And which is wrong?
But no matter.
The planet itself does not care what we call it. Our names mean nothing to it. The planet simply is what it is, as it was before humans gave it names and as it will be long after humans have faded from this universe.
Sig for hire.
Causing an environmental catastrophe at the time.
Yep, oxygen build up was a disaster for the cyanobacteria that created it and had reigned Earth for 3+ billion years. On the plus side the free oxygen enabled collagen to form, which is the substance that holds single cells together in multi-cellular organisms. We call that transition "The Cambrian explosion". The collision we are talking about occurred 3.5 billions years before the Cambrian explosion.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.