Wednesday, November 28, 2007

Studying ghost craters?

After reading the S&T article in Dec 2007, I wonder if the study of ghost crater is a worthy project.

First of all, as for fun, it's nice to have a collection of ghost crater images, rather than just taking mug shots of famous craters again and again.

Secondly, I wonder if the distribution of these ghost craters have some "scientific value". Suppose ghost crater is created by lava flow (reasonable, right?), and given the moon is always facing us at around the same face (*), when lava flows, it should have similar tidal effect like that of the earth, i.e. the lava will be thicker at the side near the Earth.

Suppose craters are formed randomly, given the thicker lava layer at the side near the Earth, we will see less ghost craters if the lava is thick enough to cover old post-mare craters, or we will see more ghost cracters if the lava is not thick enough. When I say more, or less, I mean when compare to the limb of the moon as seen from the Earth.

So, given the lava is really thick enough in the middle, we should see nearly no ghost crater there. In that case, ghost craters will be found nearly solely nearer to the limb?

And given the lava is not thick enough even in the middle, we should see ghost crater in the middle but less nearer to the limb, since it's even thinner there.

(*) But if we found it pretty close in number, does that mean the age in which lava flows is older than the time when same face of the moon is locked to the Earth?

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