I hear that a lot.  Now, I’m not going to climb up on a soap-box here, but let’s get one thing straight; Pluto was NOT named for the Disney character, the Disney character was named after the planet Pluto.

NASA/ESA Hubble, highest current resolution of Pluto

Pluto was discovered by Clyde Tombaugh on February 18, 1930, and announced March 13, 1930 (you know this, right?).  Its name was announced May 1, 1930.  Pluto the Pup was “Rover” until May 8, 1931, when the name was used in a cartoon called The Moose Hunt. That was the first time the name “Pluto” appeared for the cartoon animal.  The planet is actually named for the Roman god of the underworld, which also explains the names of its moons.

I don’t want to get fussy here, but while I’m on the subject of Pluto, it wasn’t demoted to a dwarf planet because of its size.  It was assigned the status because it hadn’t cleared its orbital path.  The three criteria which must be met for an object to be categorized as a “planet” are:

1. The object must be in orbit around the Sun.
2. The object must be massive enough to be a sphere by its own gravitational force. More specifically, its own gravity should pull it into a shape of hydrostatic equilibrium. 
   
3. It must have cleared the neighborhood around its orbit.

Pluto is certainly in orbit around the Sun; it has a fascinating orbit, and it’s definitely round.  The problem was that there was too much clutter, or debris, within its orbital path.  The thinking is that a planet would have accreted all the bits and pieces.  Of course, we may be watching the process of accretion with Pluto, which we’ll only know over time.

Of course, there’s a HUGE argument about that whole “clearing the orbital path” issue, considering how many asteroids are in Jupiter’s orbit… and Saturn’s orbit…

NASA/ESA Hubble, the Pluto system

Something else that’s cool about Pluto is that it could actually be a binary system with Charon, with Nix and Hydra it’s only moons.  I’m hoping to see some studies relating to that as New Horizons approaches.

One urban legend about Pluto that is absolutely true is that a small portion of Clyde Tombaugh’s ashes are aboard the New Horizons spaceship.

Now, everybody repeat after me:  Pluto was NOT named after the dog, the dog was named after Pluto.  Pluto was NOT named after the dog, the dog was named after Pluto.  Pluto was NOT…