Ezkerraldean

yes, it is sensible. it is the best way to explain the differences in composition between the earth and the moon.
what do you mean? on the moon or on the earth? the impact would have literally melted the impactor and most of the earth's mantle. the earth and moon would coalesce and "round themselves off" leaving no scars. since there are no erosional or depositional processes on the moon, and the fact that its surface is entirely igneous, the moon supports this.


yep. the best model is a glancing angular impact between the "proto-earth" and a mars-sized body.
The existance of another planet that impacted the earth is not isolated speculation. Models of solar system formation predict literally hundreds of mercury to mars-sized planets forming in the inner solar system, most of which get smashed up or flung away. Composition of asteroids in the main belt supports this too. Everything works pretty well.
loads of Kuiper Belt objects have moons a similar relative size to their parent as the earth to the moon. its probably not all that rare.
what does "perfect-sized" mean?

Barbarian

Maybe Muhammad split Saturn's moon Iapetus instead of Luna - at least Iapetus has the appearance of having been reassembled from two halves by someone with little experience in such matters. Even if Iapetus was the work of the saturnian Muhammad, that's the kind of feature we should expect to see on Luna too, if it was split just a few centuries ago.

On the other hand, two groups of people on two sides of a mountain, each seeing the same half-Moon could easily be told that the other group saw another piece, especially if they imagined the Moon not to float too high above the ground - perhaps they even imagined it to fly lower than the top of the mountain?

RAFH

The current consensus is the moon resulted from a collision between the proto earth and another body. Probably prior to 4.5 billion years ago, very soon after the formation of the solar system, before either the earth or the other body had solidified. So far its the best explanation for the observations available.

The reason there is no scar on the earth, it was still molten and any scar would have been healed, plus the earth has been been very active tectonically and any scars would have been destroyed; for the moon, it was formed from the material ejected by the collision and as as such would not have any scar, plus the moon also went through some extraordinary melting events that flooded its surface. The other body was either destroyed in the event or moved on to wherever.

As for how probable such an event would be, that's nearly impossible to calculate because we have no data regarding how common it wouldn't be. There's no data. However, its believed there was a much larger number of objects initially than what exists now. Its also believed most of the early planetary objects suffered such collisions.

Remember it wasn't more than 100 years ago the notion Meteor Crater was caused by an impact was unthinkable. Even the notion of the Chicxulub impact was received with incredulity, until the Levy-Shoemaker 9 impacts on Jupiter. That put it fully into the realm of reality because it actually did happen.

I've been over the arguments and supporting evidence and its a very good presentation, a very, very good presentation.

Steven Avery

Hi GD,

Definitely. Let's discuss these.

Now, how large compared to a collision that would knock off the material equivalent to the moon ? (Which then coalesces, etc.).

What remains did they leave outside the impact on the earth ?

And, more fundamentally -
How do we know there have been such collisions ?
What are the precise evidences ?

Thanks.

Shalom,
Steven Avery

Godless Dave

Much smaller.




From here: http://neo.jpl.nasa.gov/images/meteorcrater.html

Ezkerraldean

the moon-forming impact would definately bt the largest impact the earth ever suffered.

solar system accretion models predict vast numbers of impacts in the early days of the solar system. we know that just about every object in the solar system is heavily cratered. presumably this supports the model.
the few objects with few craters (venus, earth, io, europa, titan, enceladus, and that's it) all have surface-renewing processes that would erode or destroy craters. so that's explained. although all those bodies do have a few more recent craters.

the composition of asteroids and meteorites gives a lot away too. most (~75%) are chondrites - mantle material. ~10% are irons - core material. the remainder are achondrites and stony irons, which represent an undifferentiated mix.

so 85% of asteroids and meteorites are differentiated, meaning they must have once been part of a body large enough to undergo differentiation. analysis of asteroid orbits gives away the relationships between them and hints at common origins. most of the asteroids we see today are the remains of smashed-up planets.

Steven Avery

Hi Dave,

Thanks, and what remains/evidences do we have from the
conjectured moon-creation collision, much, much larger.

Shalom,
Steven Avery
http://groups.yahoo.com/group/Messianic_Apologetic

Ezkerraldean

none directly (except the moon itself!)
The reason the Giant Impact theory is favourable is that it is the only model that can explain the moon's composition, which is largely similar to earth's but with a few critical differences.
other theories (that the moon "spun off" the earth somehow, and that the moon was a seperate planet that was captured) do not explain the moon's composition, and they are much more improbable than the giant impact.

Godless Dave

The moon.

David B

I've never come across this story of Mohammed splitting the moon in two before.

Could someone post the text (in translation of course)?

It strikes me that Mohammed lived in a desert area.

And I associate deserts with mirages.

Could a mirage not be the source of the myth?

Further to the formation of the moon, the impact idea has a lot going for it.

http://www.answers.com/topic/giant-impact-theory

http://www.spacedaily.com/news/lunar-01d.html

David B