Hello Ryan,
The Earth's moon is very large, relative to the planet it orbits. In the
astronomical literature, the earth-moon system is sometimes refereed to as a
dual planetary system. The dividing line between planet-moon and
dual-planet seems to be whether the center of gravity (barycenter) of the
bodies is either in space or beneath the surface of one of the bodies (don't
quite me, though I may be wrong).
I have seen Pluto-Charon sometimes referred to as a dual-planetary system
(though now I guess it would be a dual dwarf planetary system.
-Walter
----- Original Message -----
From: <fallingfus...@wi.rr.com>
To: <meteorite-list@meteoritecentral.com>
Sent: Friday, March 18, 2011 2:44 PM
Subject: [meteorite-list] The Term "Planetary"
To the list,
I was sitting here reading some emails, and just thought...
Who in the world ever came up with the term "Planetary" in reference to
meteorites.
First of all, our Moon isn't a planet.. and secondly, to my knowledge, the
only "Planetary" meteorites in current existence have an origin of Mars.
Hence, "Martian" meteorites. Did I miss the big announcement of those from
Venus and Mercury?
Regards,
Ryan
Sent on the Sprint® Now Network from my BlackBerry®
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