RAFH

I don't understand what you are saying. What is how large compared to a collision that would knock off the material equivalent to the moon?

If you want comparisons to known impacts, the largest known impact on earth, also the oldest, is Vredefort in South Africa. It is about 300 km in diameter and about 2 billion years old. See http://www.unb.ca/passc/ImpactDataba.../vredefort.htm

That's a good website in any case.

However, the earth isn't a very good example because of the extensive weathering, biological and tectonic effects. If you look at the moon, there is a crater at the South Pole that is 2500 km across and 13 km deep. and the debris kicked out created the highest mountains on the moon. Its the largest impact basin yet found in the solar system.

The moon also has several other large one and millions of little ones.

Mars has a bunch of large impact basins, Argyre, Hellas, Isidis, Thaumasia and Utopia. They literally shaped the planet and are the largest features on the planet.

Every body in the solar system other than the gas giants show impacts.

Again, I don't know what you mean here.

From the proposed Moon originator event, it would appear the moon is it. As noted, the earth was still molten and has been too fully resurfaced to show any signs. However, the structure of the moon is very suggestive as is its mineral makeup. There is also the angular momentum of the earth-moon system and the fact the moon is receding from the earth. So it had to have started out closer. The estimate is about 80,000 km initially.

See above. See this for a hypothesis about how Mars may have been a victim as well.
http://www.sciencedaily.com/releases...0418203556.htm

See above.

This will get you going. http://en.wikipedia.org/wiki/Moon
Good primer.

Check out this as well for a general overview:
http://www.es.ucl.ac.uk/research/pla...cchi/moonf.htm

Here's more on the impact theory:
http://www.psi.edu/projects/moon/moon.html
http://www.lpl.arizona.edu/outreach/origin/
The last has some amazing graphics.

That should give you a good start. There is a lot more but its essentially the same.

The point is there have been a lot of theories as to the moon's origin, but none stood up to the evidence. The impact theory was proposed in 1984 to address the shortfalls in all the other theories, mostly the data from the moon rocks and the seismic sensor net established on those missions. Its one of the real triumphs of the scientific method. They got together without a clue except what they had didn't work. They then brainstormed as to what could have done it and then eliminated each idea by applying what that idea required in the data compared with the actual data they had. In the end, the impact won out. It was the only theory the data didn't eliminate and which accounted for all the data.

ninewands

Umm ... yes ... all of the known evidence indicates that at the time the moon formed the solar system was, in essence, a cosmic shooting gallery. Large scale impacts were not only possible, they were fairly common ... on a cosmic scale, that is.
From the modeling that has been done (which indicates that the core of the impactor actually merged with the Earth's core), the Earth should have a larger iron core than would be normal for a planet its size and the Moon should have LESS iron that a body its size normally would.

This is exactly what is found from seismic measurements of the Earth's core and analyses of moon rocks.
It's my understanding that none were involved. The modeling was more or less straight Newtonian mechanics and thermodynamics since the problem falls squarely within the Newtonian domain.
Well, everybody has to decide that for themselves, since some of the data had to be estimated (size of the impactor, velocity of impact, etc.) but the work seems entirely credible to me since it is supported by all the available evidence and is contradicted by none of it. It also provides an explanation of how two bodies with such radically different rock chemistry could have formed so close together.
First time I have ever seen an entire corps of professionals libelled in one sentence.

ninewands

Most of the large impactors that have struck the Earth over time were much much smaller then the one that caused the formation of the Moon. This is expected from statistics (large wandering bodies are much rarer than smaller ones). After all, we are talking about an impact between the proto-Earth (which was somewhat smaller than it is now) and a body the size of Mars.)
If you are asking what evidence remains on the surface of the Earth ... none. The Earth, if it was soldified at all at the time of the collison was, most likely, completely melted by the heat from the impact. Similar modelling has shown that the heat from a much smaller impact (a 400 mile diameter asteroid) would completely boil off the oceans and re-melt the Earth's surface to a depth of a couple of miles.
Collisions between relatively large bodies in the accretion disk around a newly-formed star would be normal as the chunks of matter drawn together by gravity coalesced into planets. Orbits would be especially chaotic at that time and all the "debris" would have to be "swept up" by those planets that survived the process in order to yield the type of solar system we see now. This is born out by observation of the debris disks around young stars other than the Sun.
Well, let's see ... the Earth is larger than most theories of planet formation would predict at this distance from the Sun. The Moon's size is completely disproportionate to the size of the Earth for a planet orbiting in the Earth's distance from the Sun. The Moon is extremely low in iron content for a body its size. The Earth's iron core is quite a bit larger than would be expected for a body its size. Is there an impact crater remaining on Earth? Don't be silly. Splashes would form on liquified planets, but no crater would remain because it would take several 10's of thousands of years for the planet to cool enough to re-solidify.
You're welcome.

Casper

We just recently witnessed a massive event like this on Jupiter. While the circumstances are different (gas giant) it definitely provides evidence for such collisions.

In fact, what evidence can you provide that large object impacts don't happen? Quit trolling praxeus, it doesn't suit you.

Sven

How about addressing post #20 and the link therein?

Igor Trip

From the Quran.

(al-Qamar, 54.1-2) The Hour has approached, and the moon split. But whenever they see a sign, they turn away and say, 'This is evident magic'.


Here are some of the Hadiths about the moon being split in two.

http://www.usc.edu/dept/MSA/fundamen....html#039.6724

http://www.usc.edu/dept/MSA/fundamen...ml#005.058.208


This is the longest one I can find.

Muslim Book 039, Number 6725: Also 24,26,27,28,29,30
This hadith has been transmitted on the authority of Abdullah b. Mas'ud (who said): We were along with Allah's Messenger (may peace be upon him) at Mina, that moon was split up into two. One of its parts was behind the mountain and the other one was on this side of the mountain. Allah's Messenger (may peace be upbn him) said to us: Bear witness to this.

Note that this is just three sentences long and has the moon half hidden rather than split.

This is all very poor for such a great miracle.

David B

Looks consistent with atmospheric conditions around the mountain causing refraction to me.

David B

Loren Pechtel

Since you don't know how far to the mountain you can't figure out how far the pieces are from each other. The split need not be all that far, there need not be any notable effects on the Earth.

However there would be *MAJOR* effects on the moon. I can't imagine the lunar mappers could have missed it.

Loren Pechtel

Head down to the lake, throw a big stone in. Note that it leaves no scar on the surface of the water. Therefore we can conclude you didn't really throw the stone in.

Loren Pechtel

A collision that powerful melts both bodies and thus doesn't leave much evidence.