Theories for the formation of the earth's moon

why is the catastrophic collision widely accepted?

1)it explains why the moon is made mostly of rock and why that rock was heated excessively. (moon made up of material that was part of the mantles of the proto earth and the impacting object) 2)explains why the oxygen isotope ratio is identical between earth and moon (outer layers of both are a mixture of the mantle materials of both objects) 3) catastrophic collisions were ocmmon late in the formative stages of the solar system 4) computer models show that a collision at just the right speed and angle will produce the right amount of debris in earth orbit. bad encounter geometries don't produce a moon

Fission

The moon's composition resembles that of the earth's mantle. a rapidly spinning earth could have cast off the moon from its outer layers. (nope this is not true because the earthh-moon system should contain fossil evidence of this rapid spin. it does not)

Capture

The moon's different composition could be explained if it formed elsewhere in the solar system and was subsequently captured into earth orbit. (no that's not true because something would have to slow it down by just the right amount at just the right time. also the oxygen isotope ratio reveals that the moon must have formed in the vicinity of the earth)

catastrophic collision

an object about the size of the planet mars struck the earth, heating and ejecting the outer layers of both objects. the moon formed from this ejected material.

Co-formation

it is the moon formed in orbit about the earth via accretion. (IF THAT WAS TRUE, the moon have the same composition as earth or specifically an IRON CORE) a reasonable theory that does not work

2nd fact of an theory that explains the existence of the moon

moon rocks contain few volatile substances (that is, materials that can be BAKED OUT of a rock, for example water) IMPLIES EXTRA BAKING Relative to earth

1st fact of an theory that explains the existence of the moon.

the moon's low density (3.3 g/cc) shows that it does not have a substantial iron core the earth does. thus the earth ad n moon have substantially DIFFERENT builk compositions

3rd fact of an theory that explains the existence of the moon

the relative abundance of oxygen isotopes (16o 17o 18o) on earth and the moon are identical.

what suggests that the earth and moon formed in the same region?

the relative abundance of oxygen isotopes - because the isotope ratio appears to be a fingerprint revealing where an object formed in the solar system.

why are the four hypothesis not true?

they do not address the extra baking lunar material of the moon