Friday July 29, 2005

Planet 10?

Although the circumstances (which involve somebody hacking into an website and threatening to release the data prematurely) sound uncharacteristically dramatic, astonomers at CalTech announced today that they've discovered an object in the outer solar system that's maybe 1.5 times the diameter of Pluto.  They're temporarily calling it 2003 UB313, but a name has apparently already been submitted to the IAU.  (I vote for "Persephone", even if there already is a main belt asteroid by that name.)  You can read the Wikipedia article about 2003 UB313 here, which is pretty brief at the moment, though its growth ought to be an interesting case study in rapid wiki-evolution.  (Also check out these two articles about astonomical naming conventions.)

2003 UB313's orbit is highly inclined to the plane of the ecliptic (45 degrees) and very eccentric.  That, combined with its great distance from the Sun (about three times as far as Neptune) has already re-ignited the debate about what's a planet and what's not.  Some astonomers, ironically including Mike Brown of the Caltech team, have argued that Pluto shouldn't be classified as a planet for similar reasons.  I don't see the point of the debate, frankly—any object that's (a) large enough to pull itself into a spherical shape and (b) orbiting a star (or some kind of star-remnant) is good enough for me.  So as soon as somebody gets on the ball and books some time on the Hubble Space Telescope, we'll know for sure how round 2003 UB313 is, but it's large enough that it's almost certainly spherical.  (Hmm, does Hubble have the resolution to see it as a disc?)

Tough luck for the team at the Sierra Nevada Observator in Spain, which had the misfortune to choose today to announce their discovery of another Kuiper Belt object, which would otherwise have been the largest KBO discovered so far.  Sorry, kids, but that's life in the fast-paced world of astronomy!

[Update:  Great minds think alike, they say.  On Mike Brown's web page about 2003 UB313 (and as quoted in the Wikipedia article), he says that they're obligated not to reveal their proposed name yet, but he describes the name "Persephone" as "particularly apt".  Yes!

Except: no!  He goes on to say, "Sadly, the name Persephone was used in 1895 as a name for the 399th known asteroid."  He continues:

Luckily, the world is full of mythological and spiritual traditions. In the past we have named Kuiper belt objects after native American, Inuit, and [minor] Roman gods. Our new proposed name expands to different traditions, still. We hope it is accepted by the IAU and hope afterwards that it is embraced by all.

So what do we know?  They've picked a name they think is appropriate for the planet (in the same way "Persephone" would have been approriate, as the queen of the underworld, perhaps?) from a mythological tradition that is not native American, Inuit, or Roman (or, presumably, Greek).  I'm woefully ignorant about the world's mythologies, but by applying a mixture of Google and Wikipedia, I've been able to come up with the following candidates:

  • Tuonetar, Queen of the Underworld in Finnish mythology.
  • Louhi, another Finnish goddess who lives in the frozen northern land of the dead.  She's the keeper of the Sampo (or Sampo! as it's known to MST3K fans).
  • Ereshkigal, the Sumerian (and Akkadian, Babylonian, and Assyrian) queen of the land of the dead.
  • Mictecacihuatl, the Aztec queen of Mictlan, the lowest level of the underworld.  (It's her festival that evolved into the Day of the Dead, apparently.)
  • Ilamatecuhtli, also from Aztec mythology, described here as the "aged goddess of the earth, death, and the milky way".
  • Marama, the Maori goddess of death.
  • Rohi, the ruler of the fifth level of the underworld in Maori mythology.
  • Hine-nui-te-Po, the Polynesian queen of night and death, and queen of the underworld.
  • Janas, who, according to this list, is the Sardinian goddess of death.  (Sardinian mythology—who knew?)
  • Izanami, Japanese goddess of creation and death, inhabitant of Yomi, the "shadowy land of the dead".
  • Yami, the goddess of death for the Tibetans.
  • Eingana, Australian creator goddess and snake goddess of death.  (Too much information: "She has no vagina.")
  • Marzanna or Morena, Slavic goddess of death and winter.
  • Zorya Polunochnaya, a Slavic goddess described here as the Midnight Star and goddess of death, rebirth, magic, mysticism, and wisdom.  She's part of a trio that includes the morning and evening stars, but what's the "midnight star" supposed to be?  (If they name 2003 UB313 after her, that'll be the answer!)

The best known of these is probably Louhi (she was in a movie, after all), but, as with Persephone, there's already an asteroid  by that name (3897) .  If it were up to me, I think I'd go with Tuonetar or Marama.  Of course, it would be more linguistically interesting (and entertaining) if they chose the difficult-to-pronounce Mictecacihuatl or Ilamatecuhtli.  Either of those would make the controversies about how to pronounce Uranus and Enceladus seem trivial.]

I am The Tensor, and I approve this post.
08:12 PM in Science | Submit: | Links:


TrackBack URL for this entry:

Listed below are links to weblogs that reference Planet 10?:

» Et de 10 ! from devloop :: blog
Depuis 1930, date de la découverte de Pluton, on pensait qu'il n'y avait que 9 planètes dans notre système solaire... Et bien figurez-vous q'une nouvelle planète vient d'être découverte !! [Read More]

Tracked on Aug 1, 2005 3:42:51 AM


This might end up being another nail in Pluto's coffin. I think I'm going to the "Pluto should be stripped of it's planet status" meme. It's way to eccentric to be considered a planet.

No idea what I would name a tenth planet though. Naming planets is all greek to me.

Posted by: baronger at Jul 29, 2005 9:27:19 PM

Apparently there were some reports that they'd picked the name "Lila", but Mike Brown denies this on his website.

I did a little back-of-the-envelope calculation, and if my sources and math are correct, the apparent size of 2003 UB313 should be about 2/3 of the angular resolution of the HST. Guess we'll just have to build the JWST!

Posted by: The Tensor at Jul 30, 2005 3:08:46 AM

Yes, lets make every schoolchild memorize names with lateral affricates in them. (Of course, the Aztecs were, broadly speaking, native Americans, but then so are the Inuit.)

I don't know about e.g. the IAU, but I think the public will be a lot more willing to add a planet than subtract one.

Posted by: Tim May at Aug 1, 2005 5:06:48 AM

According to a recent update on Brown's web page, there's some competition between the planetoid committee and the planetary feature committee over who has authority for this thing's name, if the special committee decides that it's a planet.

Posted by: Tim May at Aug 11, 2005 5:52:38 AM

More news! 2003 UB313 now has a moon. As the IAU committees have yet to announce an official name, they're still using the codename "Xena"; the moon has accordingly been codenamed "Gabrielle".

Posted by: Tim May at Oct 3, 2005 6:07:56 AM