>What does its composition matter? I said she was a planetologist. To planetologists, composition is everything. Composition is what the planet is, not where

>What does its composition matter? I said she was a planetologist. To planetologists, composition is everything. Composition is what the planet is, not where it is. >Indeed, to first approximation there are only three types of stuff in the solar system: Yeah, but planetologists don't stop at the first approximation. >As for the "cleared the orbit" bit, check out wikipedia's article on "Dwarf planet"; Let's see...ah. OK, here's the clause that I didn't know about: "and there are no other bodies of comparable size other than its own satellites or those otherwise under its gravitational influence" (emphasis added). The Trojans are clearly under the gravitational influence of Jupiter. Thanks.