2003 Ub 313: The Incredible Shrinking Planet?, No bigger than Pluto? Options

[Guest_BruceMoomaw_*]

(Thanks to Emily Lakdawalla):

http://sciencenow.sciencemag.org/cgi/content/full/2006/127/1

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The IAU & everyone else has to face up to one fundamental fact: the objects in the Solar System exist along a continuum of sizes, from individual hydrogen atoms to Jupiter. Defining what is and is not a planet will always be a purely arbitrary convention by any objective standard, except for the apparent distinction that a planet has to independently orbit the Sun. Maybe it's time to throw out the concept entirely...?

Well, short of that heresy, maybe we just need to distinguish between "major" and "minor" planets. If that definition were adopted, I'd say that Mercury becomes the standard minimum body, and we have eight major planets. (Let's face it: it's embarrassing that Pluto is only half the size of the Moon!)

[AndyG]

Defining what is and is not a planet will always be a purely arbitrary convention by any objective standard, except for the apparent distinction that a planet has to independently orbit the Sun.

Independently? Well, that rules out the Earth-Moon binary system then. ;-)

Andy