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33 votes

Why did Theia create only one moon if it struck Earth?

Most simulations generate multiple moonlets and streams that then fall into Earth, merge into the moon or escape (e.g. like this or this). The initial orbit tends to be close to the Earth. This means ...
Anders Sandberg's user avatar
24 votes
Accepted

If Theia really crashed into Earth, did it impact Earth's axial tilt?

TL;DR: Yes Long answer: Theia is a hypothesized ancient planet in the early Solar System that, according to the giant-impact hypothesis, collided with the early Earth around 4.5 billion years ago, ...
Nilay Ghosh's user avatar
  • 4,695
10 votes

Does the Giant Impact Hypothesis explain how the Moon circularized its orbit?

I want to point out that the Moon's orbit isn't circular now. A 0.055 mean eccentricity isn't that circular. But, onto your question. I think you're making a bad assumption on the "must have ...
userLTK's user avatar
  • 24.1k
7 votes
Accepted

What was Earth's mass before the collision with Theia?

I'm not sure if there was a significant amount of debris, however the calculation you mentioned would at least give an upper bound on the value: $ M_{piE}=\text{Greatest possible mass of pre-impact ...
Flengasaurus Physics's user avatar
6 votes

What is Earth believed to have looked like before the collision with Theia?

Greenwood et al suggest that Earth had a lot of its water (maybe upto 70%) before Theia, but I can't find anything definite saying that it was liquid, although several sites reporting on the Greenwood ...
PM 2Ring's user avatar
  • 15k
6 votes

How was Theia discovered?

One link away from the Wikipedia article you mention there is a reasonably comprehensive list: Earth's spin and the Moon's orbit have similar orientations. The Earth–Moon system contains an ...
vvotan's user avatar
  • 290
5 votes

How was Theia discovered?

Theia has not been discovered. The giant impact hypothesis is, as the name suggests, a scientific hypothesis -- an idea that proposes a tentative explanation about a phenomenon or a narrow set of ...
David Hammen's user avatar
  • 34.1k
5 votes

Was Theia not a Kuiper Belt Object?

Was Theia not a Kuiper Belt Object? Almost certainly not. The most widely accepted hypothesis is that Theia formed close to the proto-Earth, such as near one of the proto-Earth's L4 or L5 Lagrange ...
David Hammen's user avatar
  • 34.1k
4 votes

If Theia did collide with Earth, would it have produced rings? If so, would we expect to still see at least some remnants today?

First things first, but in this case, second things first. When an asteroid or moon, passes the Roche Limit, it breaks apart and forms rings around the primary body. This is a widely believed ...
David Hammen's user avatar
  • 34.1k
3 votes

If Theia did collide with Earth, would it have produced rings? If so, would we expect to still see at least some remnants today?

tl;dr Maybe it made rings, but they’re certainly not around today. The whole reason the Roche limit exists is because of tidal forces, and the whole reason tidal forces exist is because we choose to ...
Justin T's user avatar
  • 3,404
3 votes

Does the Giant Impact Hypothesis explain how the Moon circularized its orbit?

Does the Giant Impact Hypothesis explain how the Moon circularized its orbit? No, it does not. The giant impact hypothesis says that the Moon formed a handful of Earth radii from the center of the ...
David Hammen's user avatar
  • 34.1k
3 votes

Does the Giant Impact Hypothesis explain how the Moon circularized its orbit?

Well, I don't really think the GI Hypothesis can answer the orbital plan of the moon, I would say that the circular orbit of the moon today regarding the GIH is also due to other variables, like ...
Michael P. Jouanneau's user avatar

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