The Solar System Expands. I love homeschooling! Last weekend the kids were bored -- it's August -- I got to talking and telling stories and one thing led to another and soon I realized that the kids weren't able to roll off the solar system in order. While it's not a problem for Emilie, age 5, it is for Sarah, a rising 4th grader. So I gave the two older ones a project -- list the planets in order with distance, time of revolution and the source of the planet name. Of course, this led into Roman and Greek mythology, then to Norse (Thursday is Thor's day, etc.) and on to Beowulf and so on.

They've been working on their charts and reading the myths -- I was planning on laying out the solar system to scale in the street this weekend. Then, this morning I got my SpaceWeather e-mail announcing the IAU Planet Definition Committee has proposed a new definition which not only clarifies the status of Pluto (it's in), but also allows three other bodies to come in as planets: Ceres (actually 1 Ceres), Charon and [let's see if I can get the styling on this correct] 2003 UB₃₁₃.

So we're all thrilled -- what perfect timing. The kids are busy learning the new names -- Ceres is the goddess of motherly love and of plants -- and learning the exact nature of Pluto and Charon -- while Charon's been thought of as a moon -- the new definition treats Pluto and Charon as companion or twin planets. Maybe it would've been better to rename the planets Castor and Pollux (yes, I know the problems with the stars and the moon of Saturn). Or to rename Pluto as Cerberus. Charon is of course, the boatman into Hades.

And we're all wondering what they will name 2003 UB₃₁₃. Xena seems to be the most discussed possibility, I like Persephone, although if we stick with the Roman predominance, I guess it should be Proserpina. There are two reasons (and reading the wiki website, I see my thoughts aren't original): First, given Persephone's links to Hades (Pluto) in mythology, it sort of plays off on that. Second, with it's erratic orbit, it is sort of in the solar system part of the time and off on a voyage the rest.* My oldest daughter likes Egeria. You can bet there will be heavy lobbying for Vulcan.

More - Heh.

Still More: Dava Sobel on the change.
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*Here is a much better explanation as to why it should be Persephone:

If the object falls under the rules for other Kuiper belt objects, however, it must be named after some figure in a creation mythology. We have decided to attempt to follow that ruling scheme. […] One such particularly apt name would have been Persephone. In Greek mythology Persephone is the (forcibly abducted) wife of Hades (Roman Pluto) who spends six months each year underground. The mourning of her mother Demeter causes the dead of winter. The new planet is on an orbit that could be described in similar terms; half of the time in the vicinity of Pluto and half of the time much further away. Sadly, the name Persephone was used in 1895 as a name for the 399th known asteroid. The same story can be told for almost any other Greek or Roman god of any consequence […] 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.

I think the 399th asteroid gets bumped in this case -- rename it Xena. Oh, I found the above on the Wikipedia entry and this was it's source.