Meteor Mass

May 26, 2010 11:09

I'm helping a friend who's working on a science fiction novel, and the question has come up about how much meteor dust accumulates on the Earth. (The question is really focusing on the Moon: The Apollo seismometers were picking up something like 150 individually detectable impacts per year (plus the quakes), and below this was a constant noise ( Read more... )

writing, moon, space

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deckardcanine May 26 2010, 22:18:04 UTC
The Moon's surface area is about 7.5% of the Earths, or around one-thirteenth. So all of the above numbers would be divided by 13 to get a rate of fall on the lunar surface

I would expect the difference in gravitational pull to enter the equation. And possibly the fact that one side of the moon always faces the Earth. But these factors may be negligible in this case.

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level_head May 26 2010, 22:31:56 UTC
The difference in gravity has a greater effect on the impact speed than rate. On Earth, the minimum speed is about 11 kps per second, regardless of the original direction, because of our own gravity. The Moon's gravity is much less, so the escape velocity is only about 2.4kps.

Still, neither body has enough gravity to sweep out huge areas of space.

The Moon facing the Earth is part of a conundrum that has long perplexed selenologists. The other side of the Moon is very different. Much more cratered, and almost devoid of the lava "seas" that show so prominently on this side. Considering how far apart the two bodies are, it's hard to imagine that the Earth forms much of a shield. But still, the differences are there.

The crust is very different, too. Almost as though the Moon consists of two mismatched half-planets.

===|==============/ Level Head

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Innnnnnnteresting c_eagle May 27 2010, 05:23:08 UTC
I'd love to find a site that gives the speed and specs of the Earth as extimated on a scale, say, every few thousand or million years down the line... :>

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Re: Innnnnnnteresting level_head May 27 2010, 05:57:24 UTC
Surprisingly, even the largest estimates of meteor mass will have little impact -- so to speak -- on the Earth.

The post got long, but I put up a new entry just for you:
http://level-head.livejournal.com/464086.html

===|==============/ Level Head

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