This is planetary radio. Hi everyone I'm Matt Kaplan.

I'm Matt Kaplan.

Jules Vern wrote about it.

A recent movie also sent people there, but in reality our own

planet's interior remains mysterious. Our guest today knows as much as

anyone about the Earth's core and he'd like to know more. David Stevenson has even

come up with a fought-provoking way to get there. Later, Bruce Betts will drop in with the

new trivia contest. First, though, Emily wonders if bits of Earth have

traveled anywhere else in the solar system. Stick around as we get to the core of

the matter in this week's planetary radio. Hi, I'm Emily Loch Duwala with questions and answers.

A listener asked, what are the odds that we will find Earth rocks on the Moon, just like we have found

Moon and Mars rocks on the Earth.

Finding an Earth rock on the Moon is possible, but very unlikely, even for an expert looking for such a rock.

To understand why, first you have to know how we find meteorites on the Earth.

There are about 5,000 known meteorites, of which about 50 are believed to have come from Mars or the Moon.

Meteorites are collected in the highest abundance in places where solid stones are very unusual,

like farmland in Kansas and Nebraska, or blue ice fields in Antarctica.

Because stones are so rare in these environments, any stone that is found has a high likelihood of being a meteorite.

Unfortunately, the moon probably has no such stone-free

regions, so meteorite hunters there would have to examine literally millions of rocks

before they had a reasonable probability of turning up a meteorite.

Out of all the lunar samples of rocks and soil, only one millimeter-sized chip was found to have

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