Moon Over Parador

[cardero]

Where did the moon come from?

[Riverwolf]

Well, according to scientists, the moon was created when a HUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUGE rock smashed into the early earth, and a large chunk of the mantle was thrown into the atmosphere, which eventually solidified and became the modern moon.

I personally don't agree, because, while I'm no expert in astrophysics, I would expect such a colossal impact to throw the earth out of orbit, if not cause the earth to explode altogether. I personally think the moon came from the same cloud of debris and dust that made our own earth. Or in the words from my mythology, Gaia and Luna are twins, born from the same cloud, except that Gaia has two halves, Father Sky and Mother Earth, whereas Luna only has one half.

[cardero]

Originally Posted by Riverwolf

Well, according to scientists, the moon was created when a HUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUGE rock smashed into the early earth, and a large chunk of the mantle was thrown into the atmosphere, which eventually solidified and became the modern moon.

I personally don't agree, because, while I'm no expert in astrophysics, I would expect such a colossal impact to throw the earth out of orbit, if not cause the earth to explode altogether. I personally think the moon came from the same cloud of debris and dust that made our own earth. Or in the words from my mythology, Gaia and Luna are twins, born from the same cloud, except that Gaia has two halves, Father Sky and Mother Earth, whereas Luna only has one half.

I would have my concerns with that theory too. The earth doesn't have any evidence that it had been hit and there is no debris in space to indicate the earth had been hit. Also interesting is the moon's orbit which is suspiciously too precise to indicate such a chaotic origin.

[painted wolf]

well, the impact would have happened when the proto-Earth was still fairly molten. Much of the debris and possibly other 'sub-moons' would have been re-absorbed. Mind you this wouldn't be as massive as the planet on planet impact... it would be a much smaller one. Ripping off the top layers of the proto-earths crust.

This model seems to best explain the geological similarity (and key differences) between the Earth and the Moon. Things that aren't well covered by the 'same cloud' model. (or the capture theory)

Mathematical simulations of the impact model seem to cover the nature of the orbit of the moon much better than the previous models.

sources:
The Origin of the Moon
Where did the Moon come from?
Theories of Formation for the Moon

wa:do

[Riverwolf]

Originally Posted by cardero

I would have my concerns with that theory too. The earth doesn't have any evidence that it had been hit and there is no debris in space to indicate the earth had been hit. Also interesting is the moon's orbit which is suspiciously too precise to indicate such a chaotic origin.

Well, that wouldn't convince scientists, nor does it really convince me, because, as Painted Wolf says, the Earth was still mostly liquid molten rock at the time and didn't have an atmosphere. This event also would have taken place about 4,000,500,000 years ago. That there would be a modern indication of such a collision would probably be considered the greatest miracle of all time, as nothing escapes the jaws of time, and especially considering the crater left by the meteor that most likely caused the K-T event(65,000,000 years ago) is pretty much invisible now. Also, the moon's orbit would probably have stabilized over time.

One problem with why I have a problem with it, is that while I say such an impact should have knocked the earth out of orbit, maybe it had a different orbit back then, and the impact did knock it out of that orbit and into its present one. I still can't think of why my idea that such an impact might also have caused the earth to explode would be debunked other than the rock was very small, about the size of Pluto or maybe even its moon.

In the field of science, it's always wise to try and see the flaws of your own ideas, especially if you're an amateur who doesn't know all the facts and numbers.

[rojse]

The collission by a mars-sized asteroid (called "Theia" in scientific circles) is considered the most logical theory currently proposed. All the other theories, including the co-formation theory previously mentioned, fail to explain why the moon has such a high velocity in relation to earth. The impact does not cause the earth to explode, rather, it causes the earth, and Theia to break into two pieces, one of which is the moon, the other of which is the Earth.

[Troublemane]

the problem with the simultaneous formation theory is (a) the materials making up the moon and earth are signifcantly different, and (b) the moon is calculated to be moving away from the earth at a rate of 1" per year. at that rate (calculating backwards) it would have been only 13,000,000 years ago that the moon split off from earth.

I do like the collision theory, as it explains why the materials making up the moon are so different (the other object, named "theia", was vaporised maybe, and formed the major part of the moon i would guess). if this happened 4 billion years ago, then maybe gravity held the moon closer for a few billion years before it slowly worked its way free, and only recently started moving away (last 100 million yrs)---that would explain the acceleration away now. I dont know alot about physics but i do know the inverse square law--gravity decreases by powers of two as you double the distance. so the idea would be the object hit earth when both were in a molten state, and then after the collison both spun off from each other, and formed together simultaneously.

i dislike the planetesimal collision model since it makes no sense. if little planetesimals are supposed to collide with each other and form a large object then wouldnt the rings of saturn and jupiter have collided into a large object by now? it makes no sense to think they would, the gravity of the nearby large object (in this case earth) would tidally effect the smaller objects, keeping them spinning around in a diffuse mass, so they'd never collide. and if they did they'd probably just break up into even smaller pieces. i dont think it would work.

[Riverwolf]

Originally Posted by Troublemane

the problem with the simultaneous formation theory is (a) the materials making up the moon and earth are signifcantly different, and (b) the moon is calculated to be moving away from the earth at a rate of 1" per year. at that rate (calculating backwards) it would have been only 13,000,000 years ago that the moon split off from earth.

First one's easy. The stuff earth might have been made out of was heavier than that of the moon, and coalesced into a larger object in a center, while the lighter stuff stayed out in orbit, and eventually became the moon. That's only based on what little I know.

Second one's a bit trickier. First of all, there was no known mass extinction 13,000,000 years ago,(as far as I know, the most recent mass extinction was K-T, but I could be wrong) which ought to have happened if such a dramatic thing happened. You propose that maybe the moon only recently started accelerating away. That makes sense, but what started this? Well, maybe an asteroid or something knocked into it, or at least passed close to it, disrupting its orbit ever so slightly, but just enough to give it that extra boost. Problem with that is that you'd think such an event would cause the moon to spin, and as far as anyone can remember(not to mention as far as I know), the face of the moon facing Earth hasn't changed at all.

Thing is, there's too little information available on this topic. While it's a great subject for scientific debate, I don't really think anyone can say anything conclusively; all the theories have flaws that cause them to be unlikely. Who knows? Maybe it was something completely different that we haven't thought of yet.

LE GASP!! Maybe the moon's an alien spaceship!!!! (jk)