Essay

Maybe Pluto is just Pluto

By Tony Laszlo

Of all the boulders, bundles of gas and shards of rock that are flying around our solar system, Pluto has been getting the lion's share of attention lately. Now, millions of primary school children around the world (along with their teachers and the publishers of the textbooks that they will study from) want to be sure, one way or the other: Is Pluto really no longer a planet? It spins on an axis and orbits the Sun in a fairly orderly manner. It's nice and round, and has something of an atmosphere. Rather planetish.

However, Pluto is also quite tiny. Not only does it not match up in size to any of the other bodies in the "planet club," it's even smaller than that lump of cheese out there that we call the Moon. Nor does it seem to have been formed in the same way as the other planets. So, it's not very planetish, after all. Indeed, it's not too difficult to imagine that Pluto would be just as happy if it were to have a different orbit, one that would plunge it in toward the sun and then shoot it back out into no man's land again. If it were to grow a long tail of dust and ice in the process, we'd think of it as just a big comet.

Personally, I'm more interested in the discussion about Charon, Pluto's sidekick. Up until now, everyone has referred to it as a satellite of Pluto. But relatively speaking, Charon is quite large; slightly more than half the size of Pluto. While our Moon is also pretty big relative to the Earth, there is no doubt that it is the one rotating around us (roughly once every 31 days), and not the other way around. However, Pluto and Charon revolve around one another, each keeping the same face pointed at the other as if locked in an embrace — or perhaps just a staring match.

If not planet and moon, what are these two? A double planet? Alas, Pluto has lost its planetary status (barring a reversal on that decision), so that terminology is out. Twin dwarf-planets? Interlocked Kuiper Belt objects? At the end of the day, the question of what Pluto and Charon are becomes a moot point. They will simply be what they will and do what they should, uncaring about the labels that might be attached to them or whether they fit into any of the available categories, at all. Rather like that category-evading figure in the animal world, the platypus.

Some people will argue that we've got to call Pluto, Charon and all the rest of the heavenly bodies something. That's probably an accurate statement. Humans do find it necessary to put anything and everything into its own little box so that all is in order. But doesn't that say more about the limitations of the human ability to perceive the universe than about the nature of the universe, itself? Whatever else they might be, Pluto and Charon are a "celestial dance couple." If we focus a bit more on the splendor of their existence and less on how to make them fit into our pre-existing image of the universe, we might just begin to hear the music they are dancing to.

Shukan ST: Sept. 15, 2006

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