[canuck_conservative]

Mars is roughly twice the size of the moon.

Note that that's diameters. For the Moon - Mars - Earth, the ratios are roughly: 1 - 2 - 4

Volumes would be the cubes of those: 1 - 8 - 64

So the Moon, at only 1/64th Earth's volume, is actually a small chunk.

[America_Right]

Heh, yeah. Different way of looking at it, same result. :) Heck, we could take it a step further and look up densities, as well, and do a whole thing with the total mass of each body! No reason to go into that, though, since we are in total agreement on this. My only point was that a Mars-sized object hit early Earth and a bit of the ejecta eventually coalesced into our moon.

As an aside, from what I have watched/read, the Earth and the object basically destroyed each other, and were nothing but big piles (a single big pile?) of rubble for a LONG time. The early Solar system was a very dangerous place.

[SunkenCiv]

Right you are about the volume. Density also matters, the Moon has about 1/100th the mass of the Earth, Mars though is about 1/8th the mass of Earth as well as about 1/8th the volume.