I recently read through a fairly interesting book that discusses in great length the origins, or more correctly the many possible origins, of our moon.

We pretty much take it for granted that the moon has always been there and always will be there. However we don't give too much thought to how it came to be there.

Our moon is unique (in the limited observations we have of moons) in it's size relative to our planet. More interestingly than that though is that the moon is 1/400th the size of our sun while it is also 1/400th the distance from our planet to the sun. Thus, when viewed from the earth they appear to be the same size (leading to the wonder of eclipses).

I also find it interesting to consider that while the earth turns 40,000km on its axis each day, the moon travels 400km on its axis.

To give one further example of extreme oddity, there are 109.2 Earth diameters across the Sun's diameter. There are also 109.2 Sun diameters between the Sun and the Earth at its furthest point of orbit. The circumfrence of the moon is 109.2 X 100km.

So with this knowledge, and without a scientifically accepted theory on how the moon came into being, one has to wonder. Who built the moon?

Reference
Knight, C and Butler, A: Who built the moon?. Watkins Books, London, 2005.

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Kolch - Crunching for the BOINC@Australia team since July 2004.
Search for your own intelligence...

I saw a show on the national geographic channel that presented a theory that the moon is a result of a collision between the Earth and another planet back when our solar system was quite young. If it weren't for the moons creation we may not be here today.

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It's true that there is a theory, popular and accepted by most for lack of a better one, that the moon is a result of a large impact with another object. It is also true that without the stabilising presence of the moon's orbit that life on this planet would certainly be very different.

The problem is that the theory of a large impact, or the 'Big Whack Theory' doesn't add up. For starters the odds of an impact with an object of the necessary size coming at the right speed and angle to create the moon is unlikely at best. Further, such an impact would leave our earth spinning at a much faster rate. So to counter this, a second impact has to be added to the theory to slow the spin back down. Imagine the odds of that! Now also wonder about the material that impacted upon the earth. Where did it go? We know, from our examination of lunar rocks, that the moon is made of rock that came from our region of the solar system 4.6 billion years ago. That is it is made from the same material as earth.

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Kolch - Crunching for the BOINC@Australia team since July 2004.
Search for your own intelligence...

It's true that there is a theory, popular and accepted by most for lack of a better one, that the moon is a result of a large impact with another object. It is also true that without the stabilising presence of the moon's orbit that life on this planet would certainly be very different.

The problem is that the theory of a large impact, or the 'Big Whack Theory' doesn't add up. For starters the odds of an impact with an object of the necessary size coming at the right speed and angle to create the moon is unlikely at best. Further, such an impact would leave our earth spinning at a much faster rate. So to counter this, a second impact has to be added to the theory to slow the spin back down. Imagine the odds of that! Now also wonder about the material that impacted upon the earth. Where did it go? We know, from our examination of lunar rocks, that the moon is made of rock that came from our region of the solar system 4.6 billion years ago. That is it is made from the same material as earth.

When the solar system was young there were possibly up to 20 inner planets orbiting the sun. So there couldve very easily been a collision. As for the second impact the moon has been slowing the Earths rotation ever since its creation. All we know of the Earths material is whats here. So it could be both of the planets material combined. We just don't know and wouldn't know for sure unless we could take a sample of the Earth's crust from before the impact. Also both the Earth and the other planet were terrestrial so their material would logically be close to the same composition and such.

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Why do you believe the earth would have had to have been accelerated in its spinning by a collision as opposed to being slowed down? One is just as likely to have occured as the other!

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Founder of BOINC team Objectivists. Oh the humanity! Rational people crunching data!
I did NOT authorize this belly writing!

It would seem that yes, one is just as likely as the other. Except it is the lady that developed the best models to support the Big Whack Theory, Dr Robin Canup, Assistant Director of the Department of Space Studies in Colorado, who has had to admit that the theory's biggest flaw is that it cannot take into account the current rate of spin of the Earth. Canup is hoping to re-model to account for the current rate of spin.

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Kolch - Crunching for the BOINC@Australia team since July 2004.
Search for your own intelligence...

Other clues that the earth and moon are products of a collision include earth's enormous iron core, the moon's composition of mostly crustal material, and the fact that the moon's small core is offset from its center in the direction of earth. I think those are hard to explain without the collision.

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I think those are hard to explain without the collision.

True enough, but it follows that they don't make the collision the only explanation.

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Kolch - Crunching for the BOINC@Australia team since July 2004.
Search for your own intelligence...

For Immediate Release

Who Built the Moon?
The Possibility of Intelligent Design

I think this says it all,and no I did not have to hunt very long to find this snipet it was about the fifth or sixth result in google.

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Old enough to know better(but)still young enough not to care

i believe this is the link you are referring to. Though I'm not sure how this weakens my point. We must consider the possibilty that the moon was constructed by some way other than natural processes.

As unlikely as this may seem, it is no less likely than any theory for natural creation that we have developed to date...

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Kolch - Crunching for the BOINC@Australia team since July 2004.
Search for your own intelligence...

i believe this is the link you are referring to. Though I'm not sure how this weakens my point. We must consider the possibilty that the moon was constructed by some way other than natural processes.

As unlikely as this may seem, it is no less likely than any theory for natural creation that we have developed to date...

Intelligent design of the moon is a theory in search of facts to support it just like all so called 'Intelligent Design' theory.

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Founder of BOINC team Objectivists. Oh the humanity! Rational people crunching data!
I did NOT authorize this belly writing!

An article published by Jeanna Bryner on the New Scientist website. Dated 22nd August, 2006. Headline reads; 'Moon Chemistry Confirms Violent Origin.'
Apparently, the European Space Agency's orbiting craft, known as 'Smart 1,' has just finished its first detailed chemical mapping of the lunar surface. Calcium and magnesium has been found. Calcium is supposed to be found inside the Earth. The article suggests that the moon's apparent chemical composition lends support to the theory that is was created naturally by a collision. I don't know if it has been proved beyond all doubt, but it seems that scientists might accept this idea more readily - that the moon is a natural satellite.

Susan.

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'No one can make you inferior without your consent.'
Eleanor Roosevelt.

Can I also add that I have a newspaper cutting of an article about the book, 'Who Built the Moon, by Alan Butler, and Christopher Knight. I haven't read the book myself, but apparently they believe the moon to be hollow. They also say that the people who built the moon were supposed to be human travellers from the future. I find that difficult to swallow, personally.

Sue.

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'No one can make you inferior without your consent.'
Eleanor Roosevelt.

They put forward 3 possible groups to create the moon. They are God, who works in mysterious ways and is apparently willing to sacrifice the lives of a few for the good of many. Far from the perfect God that i'd been taught to pray to. Another is aliens, who quite possibly have the technology, and know-how to complete a project as large as building the moon. The question is why would they do so? The final possible creator of the moon is indeed humans from the future. It is probable that we would have the technology and know-how at some point in the years to come. It is also apparently becoming clearer to physicists that time-travel is theoretically possible. Yet we continue to disbelieve in it due to our inability to wrap our heads around the paradox's it may create.

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Kolch - Crunching for the BOINC@Australia team since July 2004.
Search for your own intelligence...

The coincidences of measurement Kolch mentions are pretty much approximate. Particularly the distance between earth and Moon, a distance which has been stretching ever since the two were formed.

As Jim said, the Moon's iron core is slightly offset towards Earth, indicating the Moon was molten at some stage, allowing the core to move under influence of Earth's magnetic field.

As for theories the Moon is artificial... Robert is right... it is a theory in search of facts to support it.

Walla's mention of the solar system is a well known and respected theory. That is, the solar system was a pretty crowded place in it's early days, with large and small objects all over the place. Collisions would have been commonplace. Some of these collisions would have been destructive, some constructive, depending on a multitude of circumstances, including the relative speed and mass of the objects concerned.

The entire solar system may, at one time, have looked rather like the present asteroid belt, where chunks of rock, ice, etc, are prevented from combining by Jupiter's massive gravitational pull.

Many planetary size objects may, indeed, have been "expelled" from the solar system during this phase. This theory is backed up by the discovery of "Planemos", discussed in other threads.

I do, however, remember reading a serious book on astronomy before I reached teenage, which suggested one of Mars' moons may be hollow, based on measurements of it's orbital motion.

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From SMART-1 on the trail of the Moon’s beginnings

The D-CIXS instrument ... has taken a step towards answering the old question: did the Moon form from part of the Earth?
............
However, the more scientists looked at the details of the moonrock, the more discrepancies they found between them and the earthrocks. Most importantly, the isotopes found in the moonrocks did not agree with those found on Earth.
............

From SMART-1 on the trail of the Moon’s beginnings

The D-CIXS instrument ... has taken a step towards answering the old question: did the Moon form from part of the Earth?
............
However, the more scientists looked at the details of the moonrock, the more discrepancies they found between them and the earthrocks. Most importantly, the isotopes found in the moonrocks did not agree with those found on Earth.
............

Next paragraph reads:-"The get-out clause is that the rocks returned by the Apollo missions represent only highly specific areas on the lunar surface and so may not be representative of the lunar surface in its entirety," says Grande; hence the need for D-CIXS and its data.

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Old enough to know better(but)still young enough not to care

From SMART-1 on the trail of the Moon’s beginnings

The D-CIXS instrument ... has taken a step towards answering the old question: did the Moon form from part of the Earth?
............
However, the more scientists looked at the details of the moonrock, the more discrepancies they found between them and the earthrocks. Most importantly, the isotopes found in the moonrocks did not agree with those found on Earth.
............

Next paragraph reads:-"The get-out clause is that the rocks returned by the Apollo missions represent only highly specific areas on the lunar surface and so may not be representative of the lunar surface in its entirety," says Grande; hence the need for D-CIXS and its data.

Has no-one thought of what seems obvious to me???

If earth WAS struck by another planet, perhaps the make-up of the other planet was different to that of Earth. Much of the material making up the theoretical Mars-sized planet would have combined with the Earth, while ejecting material that would later become the Moon.

In a cataclysmic event such as the theory suggests, I feel it would be natural to assume some minerals were transferred between all three objects, and that the distribution would differ between them, as a result.

If any extra-terrestrial geologists/astrophysicists out there would like to shoot me down in flames, please do! :)

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In my humble opinion, the moon is a sister world that formed in orbit around Earth as the Earth formed, some 4.5 billion years ago.

The moon has the same oxygen isotope composition as the Earth, while Mars rocks and asteroids from other parts of the solar system have different compositions.

This shows that the moon formed form material formed in Earth's neighborhood, which leads me to believe that if it didn't form together with the Earth, maybe it formed nearby and then was captured into orbit around Earth.

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/Mav

We have lingered long enough on the shores of the cosmic ocean.
We are ready at last to set sail for the stars.
(Carl Sagan)

In my humble opinion, the moon is a sister world that formed in orbit around Earth as the Earth formed, some 4.5 billion years ago.

The moon has the same oxygen isotope composition as the Earth, while Mars rocks and asteroids from other parts of the solar system have different compositions.

This shows that the moon formed form material formed in Earth's neighborhood, which leads me to believe that if it didn't form together with the Earth, maybe it formed nearby and then was captured into orbit around Earth.

That was the favoured theory when I was at school in the 1960's Until the current one of a Mars size planet colliding with the proto Earth with the
'splash' going to make up the Moon henc its simmilar chemical/mineral makeup
plus this mars sized object must have formed near enough to the early Earth to be able to collide with it in the first place imho.As for time travelers coming back in time WHY??????Te only way that this is going to be solved one way or another is for a 'long'term mission to the Moon to return not just a few kilos of surface rocks but a dep drilled core sample from several locations probibly several hundred over many years.

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Old enough to know better(but)still young enough not to care