![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
(no subject)
Aug. 16th, 2006 10:15 am"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."
This is the definition for "planet" being considered by the International Astronomical Union. By this definition, it seems we have 12, and potentially 53 or more, planets in the Solar System.
The new planets would be:
Ironically, Mike Brown of Caltech, who discovered Xena and who would therefore go down in history as the discoverer of the 12th planet, opposes the proposed definition:
Objects which are expected under this definition to qualify as planets include the plutons Sedna, Orcus and Quaoar, and the large asteroids Vesta, Pallas, and Hygiea. [source] (Huya also?)
This is the definition for "planet" being considered by the International Astronomical Union. By this definition, it seems we have 12, and potentially 53 or more, planets in the Solar System.
The new planets would be:
- Charon, presently considered the moon of Pluto but elevated to planet status because Charon and Pluto both orbit a point in space external to both of them. Charon and Pluto are thus a double-planet system.
- Ceres, the largest of the asteroids between Mars and Jupiter. It was originally considered to be a planet when it was discovered in 1801 but was demoted when it was found to be among many small objects -- asteroids -- orbiting the sun in a coherent band.
- Xena, the transneptunian object (TNO, now to be called "plutons") discovered in 2003. "Xena" is not the planet's "official" name, so it might be time for a letter-writing campaign (for those of us who really, really like that there's a planet named Xena).
Ironically, Mike Brown of Caltech, who discovered Xena and who would therefore go down in history as the discoverer of the 12th planet, opposes the proposed definition:
"It's flattering to be considered discoverer of the 12th planet," Brown said in a telephone interview. He applauded the committee's efforts but said the overall proposal is "a complete mess." By his count, the definition means there are already 53 known planets in our solar system with countless more to be discovered.
Brown and other another expert said the proposal, to be put forth Wednesday at the IAU General Assembly meeting in Prague, is not logical. For example, Brown said, it does not make sense to consider Ceres and Charon planets and not call our Moon (which is bigger than both) a planet.
Objects which are expected under this definition to qualify as planets include the plutons Sedna, Orcus and Quaoar, and the large asteroids Vesta, Pallas, and Hygiea. [source] (Huya also?)
