[meteorite-list] The Term "Planetary"

[Walter Branch]

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: <fallingfusion at wi.rr.com>
To: <meteorite-list at 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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