Wednesday, February 18, 2004

Athens, Rome, Los Angeles:

No, not the Olympics, but the seat of cultures that have given us the mythology and deities we choose to immortalize in the skies. Athens gave us the Greeks, Rome gave us the Romans, and Los Angeles gave us the Tongva.

"Los Angeles? Tongva?"

Yes, it is so. Chad Trujillo and Mike Brown, of Caltech's Division of Geological and Planetary Sciences (GPS), have named their discovery, the largest "minor planet" beyond Pluto, Quaoar, after a god of creation in the legends of the Tongva, Native Americans indigenous to the Los Angeles Basin.

You might comment that this choice is somewhat parochial. After all, the Greeks and Romans had a very large impact on subsequent civilizations, many of them far removed in time and in geography. You might say it would be telling if we asked 100 randomly selected citizens (even from the L.A. basin) if they had heard of a) the Greeks, b) the Romans, and c) the Tongva.

Well, there is a website about c), of course. It turns out that the Tongva are an as-yet Federally unrecognized tribe of about 300 people.

I would suggest a few minutes perusal of the full list of Minor Planet Names. A few guffaws are guaranteed ("Arthurdent" "Tweedledee/Tweedledum" "Zappafrank"). "What about the deities of the Chibcha? I cry out... I want a planet called Tequendama!"

However, all this is old news, including the debate about the name. After all, the discovery dates from June of 2002, and the name 'Quaoar' has since been accepted by the International Astronomical Union. You can see information on the IAU naming proces and guidelines here and here (N.B.: despite many huckster's ongoing attempts to convince you and your wallet otherwise, naming a star for your sweetheart ain't official).

The name Quaoar does meet the IAU criteria (although I'm not sure about 'easily pronounceable'), and I bet having the largest body discovered since Pluto went a long way towards meeting the political goal of having the Tongva tribe Federally recognized. I can imagine that the Tongva elders' consideration of this idea was an extremely interesting discussion.

What got my attention was an article in the GPS Alumni Newsletter by Trujillo that talked about the ongoing search for other bodies like Quaoar.

By using the IRAM telescope in Spain and the Hubble, Trujillo and Brown have determined that Quaoar is 1,250 km in diameter, which makes it about as large as all the known asteroids put together. They are in the middle of a robotic search of the entire sky using the Oschin telescope on Palomar, which by the end of 2004 will indicate if there are any additional bodies like Quaoar.

Trujillo's surprising comment was the following:

"Since beginning this project, we have only had time to examine about 7 percent of the sky for the presence of very large bodies like Quaoar, so we think that there should be about ten more of similar size that are still undiscovered, a few of which may be even larger than Pluto." (Pluto is about 2,300 km in diameter)

(NASA and A. Feild/STSci)

If there are bodies discovered larger than Pluto, this will certainly add fuel to an ongoing debate about how many planets there are in the Solar System. Surprisingly, the debate is not whether Quaoar should be an additional planet, but about whether Pluto should be demoted, or thrown out. There has been sufficient debate and confusion to have the IAU reconfirm that Pluto is indeed a "planet."

It's not as simple as one would think. Simply saying that planets are round and orbit the Sun, would give us many more: Ceres, about 914 km in diameter; Pallas (522 km); and Vesta (~500km). In the outer solar system, among the Kuiper Belt, consider this crop:

(Gerhard Hahn/DLR, Astrovirtel, ESO, ESA, Institute for Astronomy)

When we add 2001 KX76 (also referred to as "Ixion"), Varuna, and all these other 1,000 km class objects to the list of 'planets,' and remember that they are being added to on a yearly basis, we can see that the list of planets will get out of hand quite quickly.

We've been there before, when Ceres' discovery in 1801 was quickly followed by the avalanche of Pallas, Juno, and Vesta, and the post-1845 deluge of Astraea, Hebe, Iris, Flora, Metis, and Hygeia.

(There are a lot of bodies out there, most of them much smaller, but in impressive numbers, as in this 100-year animation of the outer solar system made by the folks at Harvard's Minor Planet Center)

The historical list of eight plus Pluto was soon re-established, and it will likely live on for historical reasons rather than a truly consistent ontological naming system.

Despite Quaoar, Ixion, Varuna and their ilk.