I was watching a Discovery Channel special the other night about "our moon" and how it was created... I'd never really thought about it before, and this wasn't something taught to me in school, so I decided to discuss it here.

On the TV program, they said that Earth had a sister planet, Orpheous ( or something like that ) and that it finally collided with the Earth, and basically created our Moon.

Heres what one site says about it :

The moon is Earth's closest celestial neighbor. It has a huge influence upon our lives, governs the tides (the sun plays a small part, but not nearly as much as the Moon), and is responsible for eclipses. Some biologists say that the moon is even responsible - in part - for life on Earth, for without the tides causing currents and mixing of chemicals, life might never have formed.

There are four main theories about the creation of the moon, although only one is generally considered to give an accurate description of what actually occurred.

The first theory states that the moon was created the same way the planets were - through the coalescing of gas and dust during the solar system's formation. The second theory says that the moon is a captured asteroid. The third theory says that when the Earth was first formed it was spinning so rapidly that it split in two; this is often referred to the "fission" theory*.

The fourth theory is the one that most scientists currently believe is correct. It states that when the Earth was quite young, a Mars -sized planet crashed into it. The planet crashed with such speed that it was completely destroyed, and almost destroyed the Earth. The planet was coming in with such force that when it was destroyed, the molten iron in its core continued to travel through Earth, to eventually be included it its core. This explains why the Moon has very little iron. The crash, comically dubbed the "Big Splash," sent tons of rock and debris into orbit. These fragments eventually coalesced to form the Moon. The tidal and rotational forces in play also account for why the moon's day is exactly the same as it's "year."

So wich is it.... I know that many of our ATS peeps out there will have opinions and answers... so let's have it..

IMHO a planetoid crashing into Earth, with subsequent splash of the debris flying out into the orbit and coalescing, makes the most sense. The lack of iron on the Moon is mentioned in your quotes.

I prefer the "capture theory myself.
The 4th scenerio, has a couple of drawback to it for me to accept it.
If you go by it, then you would (probably) have more than one moon.
Also the ejection of material to the Roche limit would require one heck of a collision.
The lack of a large amount of iron in the moon's core I have to question how they were able to determine this. As the normal method of determining the composition of extra-terrestrial bodies is through the use of spectral analysis.
This method would indicate iron deposits on - near the surface.
The moon being as cold as it is, the core could very well be solid. Without there being an expedition to drill down to the core to verify it's composition, how can they be sure?

I heard somthing like that i read that a mars sized chunk of stuff hit earth and spun debree into space and that made the moon dont think its true.

Most scientists prefer the Collision Theory. Earth was hot, molten, something hit it. A large piece flew off, became the Moon. It accounts for pretty much all of the behaviors of the moon, the age, etc. It's very close, I think, to being accepted as the "truth" as far as we know.

It's not particularly hard to happen, either.

I think if the moon was created by a collision with earth then there should be plenty of evidence to support it. Such a collision would have had to release massive amounts of debris that would still be orbiting the sun allthough not exactly folllowing the earths path.

Maybe the earth and mars collided and thats what caused mars great scar? heh

I would be more evidence out there floating around.. has anyone even looked?

X

It's the only way to go!

The Moon doesn't have the same geological make-up of Earth; in other words, it could NOT have been created by any Earth moving scenerio, because it isn't made of the same mineral/geological percentages.

*This is how we know that some meterors come from Mars. Same geological make-up. Our moon doesn't have it.*

The Moon and Earth don't fit the generalized ideas of planet/moon size ratios. Our moon is way to big to have been spun from the same gas cloud, and still be tethered to our gravity field.

*Pluto and Charion are not considered planet/moon, but rather either a double planetoid (or double moon) from the Kipper Belt (Kipler?). Some believe that Charion, or Pluto, were actually moons of Uranus or Neptune.*

I go for the capture theory.

In my opinion, the Moon was probably a satelite of either Jupiter OR the planet which now makes up the asteroid field. I know, it smacks of Stichlin or other psedo-astronomers, but it makes more sense then the "Bulge" theory and the "shattered impact"... especially when you consider that if the Moon was a part of our world, it should have the same make-up compensation.

Cut a finger off, and does it become something else? Does it change its DNA to match that of a fly or a fish? No. We will still know that it was a finger. Same thing about the Moon.

I think the collision/glancing blow theory is most plausible to me.
It helps explain the 23 degree tilt of our axis.
I think the Pacific basin, might be the source of the material..

The whole scenario may explain how plate tectonics were put into motion.

As far as the capture theory. My biggest problem with that one, is the relative size of the moon to the Earth..It's pretty Big, when compared with other planetary Moons..again, relatively speaking..
Capturing something that large would have been tough.

I would think, too, that a capture method could better explain the axis tilt then a bulge/impact.

Here we sit, at a near vertical axis... along comes a great celestrial object... It shoots past us, pulling upon our planet (come to think of it, the Pacific Basin COULD also be the side closest to our new neighbor)... but because of our gravity, instead of speeding past, it slingshots around, whipping us in a galactic tug of war... our axis twists and turns as the moon whips around, drawing closer, following its path... eventually, inertia dampens as the tug of war continues, to the point in which the moons forward momentum is held bonded to the earth's rotational direction.

Imagine the possibilities!

1. World wide floods (yeah, as if there are ANY mention of them in history)

2. Mountians rising from nothing! (think about it, there are sea shells on mountian tops?)

3. The world suffering from daylight alterations (any 'sun stood still' or 'sun moved backwards' legends).

Originally posted by Xeven
I think if the moon was created by a collision with earth then there should be plenty of evidence to support it. Such a collision would have had to release massive amounts of debris that would still be orbiting the sun allthough not exactly folllowing the earths path.

Not necessarily. A lot of that material would have been taken back to the Earth or Moon, and wouldn't be noticable at all by now. Plenty of other pieces would fall into the Sun, not having enough energy to orbit. There are undoubtably a few legacies, but nothing we'd notice.

But wouldn't an impact left a visible ring, like with our larger planets? They all have them, and speculation is because of lunar impacts (with each other).

I would think that there would be some residue floating about. If Jupiter and (especially) Saturn haven't absorbed their rings, wouldn't it stand to reason we wouldn't have as well?

The impact theory is also flawed...

It requires that our world was still is a semi-liquid state... solid enough, but soft enough to rebound and recover. So then, what hit us? If the universe was supposedly created/formed at the same time and same manner, what was solid enough to rupture our integrity?

Colby 4:19
And on the Eighth Day, God said "Let there be CHEESE."
And so cometh the Moon, bringeth the light to our nights so we may never be without cheddar, praise be to the Lord.
Behold, the power of cheese.

>lol I got docked 20 points for making this post. awesome.



[edit on 23-5-2005 by apc]

There was a visible ring, probably, I wasn't there, so I can't be totally positive.

The persitence of a ring system relies on a system of moons and moonlets. Both taking from, and recontributing to the ring systems..

The mathematical models that I have seen, also predict, that a glacing blow impact, could form a pretty good sized moon within a month or so. The tiniest of particles could even be blown away by the solar winds. Comets support this idea somewhat, because most have barely a dust tail until they get inside Jupiters orbit. Which helps explain why outer planets can retain even the whispiest of rings.

As far as the semi-liquid state goes, I think that is close..A crust, around a mantle that was hotter than today..There may have even been oceans present at the time..



[edit on 23-5-2005 by spacedoubt]

Originally posted by spacedoubt
The persitence of a ring system relies on a system of moons and moonlets. Both taking from, and recontributing to the ring systems..

What he said. If you'll notice, Saturn has a HUGE amount of shepard moons. Their sole purpose is to keep those rings intact, hence the name. If it weren't for them, we wouldn't have the awesome ring system we do. The same goes for the others.

I first read moon creation theories when i was in grade school and checked out a book on the moon with some fantastic artwork done pre-apollo copywrite.

The collision/seperate was what made sense for me. tidally locked, receeding orbit, pacific basin, similar materials, etc.

I prefer the collision theory, it makes more sense conceptually and mathematically. Sounds like a winner to me.

Originally posted by elevatedone
The planet was coming in with such force that when it was destroyed, the molten iron in its core continued to travel through Earth, to eventually be included it its core. This explains why the Moon has very little iron.

The moon, it should be noted, is made up, almost entirely, of the same sort of material as the crust of the earth. I don't know about the moon not having a core because this other planets core settled to the center, I'd think that rather the earth is solely composed of earth crust because only earth crust was ejected. The moon's material is very very similar to the material that is the crust of the earth.

Its very unlikely that it'd've been caused by conglomgeration in the early solar system, ie out of hte same stuff that the rocky planets are composed of. The earths makeup was once more or less uniform, then it started to differentiate, resulting in a metal core, the mantle, and the rocky crust, this is a planetary process. To get a thing made up of crust, you need a planet, or to knock it off of a planet, not form on its own. The geochemistry of the moon seems to confirm that its the same as the crust of the earth.

kenshiro
The lack of a large amount of iron in the moon's core I have to question how they were able to determine this.

All interesting points. I suspect that the lack of an iron core in the moon is determined as its determined for the earth, that is an analysis of the movement of sound waves thru the moon

Xeven
I would be more evidence out there floating around.. has anyone even looked?

The moon itself is the evidence. What else would there be? Keep in mind, the collision of planets if a trememdous thing, resulting in magnificent releases of heat, vapourizing rocks, and the gravity of these two planets would tend to prevent things from flying off in to the far reaches of the solar system.

soothsayer
The Moon doesn't have the same geological make-up of Earth; in other words, it could NOT have been created by any Earth moving scenerio, because it isn't made of the same mineral/geological percentages.

Correct, its make up matches that of the earth crust, not the earth as a whole.\

Mountians rising from nothing! (think about it, there are sea shells on mountian tops?)

These things are far better explained by uniformitarian processes than the super tidal pull of a rocketing nearby planetoid.

It requires that our world was still is a semi-liquid state

I think that the theory implies that the core and crust had differentiated and started to solidify

the universe was supposedly created/formed at the same time and same manner, what was solid enough to rupture our integrity?

Not the universe, but the solar system, and why would one have to be molten but the other solid in order to have an effect?? The objects could've been of equal consistency, their gravity is what is forcing them together. Imagine a lava lamp, where the material is also magnetic, and two huge bulbs race torwards each other, they will merge. Indeed, imagine that they are spining, and hit, its not unthinkable that some of the outside of each will blurt out.

But wouldn't an impact left a visible ring, like with our larger planets?

Why? This is two planets merging, not one being hit by a smaller impactor and spurting out debris.

The world suffering from daylight alterations (any 'sun stood still' or 'sun moved backwards' legends).

This is not something that is going to have happened while man was around. If the movement of the massive moon was affecting the rotation of the earth, such as above, I can't imagine that people'd be able to survive the wildly shifting planetary movements.

spacedoubt
I think the Pacific basin, might be the source of the material..

You're not going to find an impact crater or anything like that, the impact was far far too destructive.

The whole scenario may explain how plate tectonics were put into motion

Interesting, but unlikely. The impact would destroy any proto-plates that were forming. Plate Tectonics seem to be driven by other processes and don't seem to require this jump start too.