Is It Is, Or Is It Ain't, A Planet?

(A follow-up to this post about Pluto's planetary status.)

More numbers:

Mars: equatorial diameter (de) = 6,805 km
Ganymede (Jupiter): mean diameter (dm) = 5,262 km
Titan (Saturn): dm = 5,150 km
Mercury: de = 4,879 km
Callisto (Jupiter): dm = 4,821 km
Io (Jupiter): dm = 3,643 km
Moon (Earth): de = 3,476 km
Europa (Jupiter): dm = 3,121 km
Triton (Neptune): dm = 2,707 km
Pluto: dm = 2,306 km

So there are 7 planetary satellites, including our own Moon, that are larger than Pluto; two of them are even larger than Mercury, which no-one disputes is a planet. So our definition of 'planet,' invoking as it does relative size within planetary systems, is silly.

There's an assumption that the technical and vernacular definitions of 'planet' should be the same. This need not be the case, and it certainly won't assist our understanding of the universe to keep it so. As we've all been reminded by recent events, the technical and vernacular definitions of 'theory' are not the same. Nor are they for 'soil,' for 'fruit,' for 'force,' 'gene,' 'monkey,' or 'universe.'

If Pluto is a technical planet, then we live in a binary planetary system in a minimum-16–planet solar system. I think that's pretty cool. It's certainly a lot more Star-Trekky.