The Tenth Planet

Victoria CalLady QED · Posted: Thu Feb 02, 06 11:49 pm

What do you think about the discovery of 2003 UB313, supposedly the tenth planet in our solar system? (If you haven't heard about it, here's a NASA article.) The International Astronomical Union is going to meet (no sooner than August) to decide whether it's a planet or not. See http://www.tenthplanet.info/.

Gwenhwyfar Bychan · Posted: Mon Feb 06, 06 7:45 pm

I'm not sure that any agreement on whether it's really a planet or not will be made...although I don't know the particulars. When the others were determined to be planets, there wasn't much room for argument because of the definition used or because of the more localized nature of the decision. I mean when William Herschel discovered Uranus, did he really have to convince anyone besides the Royal Society in England? Now everything is so global. This decision has to meet a more widespread approval...But I could be wrong!

If they do decide that it's really a "planet," I hope they name it Fama, after the Roman goddess of popular rumor! Laughing

A fitting name, don't you think? Wink

-GB

Evan Pederson · Posted: Sun Feb 12, 06 12:15 pm

The way it looks to me, I think there has to be a new class of "sub-planets" defined. Pluto and 2003 UB313 should both be included. 2003 UB313 is probably larger than Pluto, so if Pluto is a planet, there's no reason 2003 UB313 shouldn't be. But if many more similar "Kuiper Belt" objects are expected to be found, then we will probably keep running into this problem. Many of the objects that are out there are probably smaller than Pluto, making them too small to be "planets." But since they are all part of the same "group" it would be similar to calling just a few of the larger asteroids planets.

There was an other discovery that related to this in the late '90's. The space probe Galileo found an asteroid that had a moon. From what I remember, until that point, one of the informal definitions of a planet was that it was an object that had a moon. (Although off the top of my head, I can't remember if Mercury has a moon or not.) This gave new fuel to the people who had always debated the classification of Pluto as a planet.

Gwenhwyfar Bychan · Posted: Mon Feb 13, 06 7:07 pm

Victoria CalLady QED · Posted: Fri Feb 17, 06 9:56 pm

I like Fama as the name, sis.

Interesting point abt the Kuiper Belt, renaistre. I doubt anyone'd want to "demote" pluto, though.

Evan Pederson · Posted: Wed Mar 01, 06 3:11 pm

Gwenhwyfar Bychan · Posted: Wed Mar 01, 06 10:09 pm

Evan Pederson · Posted: Thu Mar 02, 06 3:25 pm

Hmm. This could get really sticky. Maybe we'll end up with Pluto not being a planet, and the Moon not being a moon. Shocked

Gwenhwyfar Bychan · Posted: Sat Mar 04, 06 5:49 pm

Victoria CalLady QED · Posted: Wed Aug 30, 06 12:03 am

Gwenhwyfar Bychan · Posted: Wed Aug 30, 06 1:05 pm

I'm glad that they demoted Pluto too. Those two needed to be classified together. -GB

Thomas Bombardier · Posted: Mon Mar 24, 08 9:48 am

Wow, this is an old thread, but I couldn't resist (being at NASA and all). I hope everyone's aware that we actually have 11 planets in our solar system? That obviously includes three dwarf planets...Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Eris.

Mr.X (Heath Harper) · Posted: Tue Mar 25, 08 10:42 am

Thomas Bombardier · Posted: Tue Mar 25, 08 11:24 am

Mm, it's a dwarf planet. The basic definition according to the International Astronomical Union (IAU) is that a dwarf planet must have sufficient mass to generate enough gravity to assume hydrostatic equilibrium and become nearly spherical. However (unlike regular planets), it does not need to have cleared its immediate neighborhood of "planetesimals." It is also not a satellite.

Wikipedia does note that being classified as a dwarf planet does not preclude classification as an asteroid as well. Ceres might be both, but it is recognized by the IAU as a dwarf planet, along with Pluto and Eris.

By the way, this classification update was adopted in 2006. Wink