Science: 12 Planets!

Not since Pluto was discovered has any event changed the outlook of the solar system so much. The picture above, courtesy of the IAU, is certainly one that you'd better get used to. With the newest draft definition of a planet developed by the IAU, our solar system has gained a minimum of 3 new planets; Charon, Ceres, and 2003 UB313 (Xena). A dozen or so other planet-like objects may also join the orbiting bandwagon around our sun in the near future. Welcome to 2006 - when we started having 12 planets.

Here is the new draft definition of a planet:

A planet is a celestial body that (a) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (b) is in orbit around a star, and is neither a star nor a satellite of a planet.

Heh. Astronomy textbook publishers are probably wetting their pants as we speak, eager to replace the now millions of books that have suddenly become obsolete.

I'm just glad that they've finally come to their senses and pumped out a definition. An object in the black of space is now either a planet or not. No more "ummm..uhh..yea..maybe..." from astronomers.

The fact that Charon was classified as a planet baffled me at first. After all, wasn't it always considered as Pluto's moon? However, given that Charon has a mass that is significant enough to be considered a planet, and that it is gravitationally linked to pluto, it is counted as a "double-planet". (http://www.iau2006.org/mirror/www.iau.org/iau0601/iau0601_Q_A.html)

Also with the planet definition is the new "pluton" definition. This group includes all planets that require 200 years to orbit their sun, of which Pluto, Charon, and Ceres are part of. Because of their generally high-tilted, elliptical orbits, these planets are thought to be different enough to be classified in a collection of their own. The "planets" currently under consideration would be plutons.

What a wonderful universe that we live in.