Thursday, August 24, 2006

Pluto demoted

The International Astronomical Union has come up with a new definition for "planet," one which leaves Pluto off the roster. From William J. Kole, AP, as published at ABC News:

...The decision by the IAU, the official arbiter of heavenly objects, restricts membership in the elite cosmic club to the eight classical planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

Pluto and objects like it will be known as "dwarf planets," which raised some thorny questions about semantics: If a raincoat is still a coat, and a cell phone is still a phone, why isn't a dwarf planet still a planet?

NASA said Pluto's downgrade would not affect its $700 million New Horizons spacecraft mission, which this year began a 9 1/2-year journey to the oddball object to unearth more of its secrets.

But mission head Alan Stern said he was "embarrassed" by Pluto's undoing and predicted that Thursday's vote would not end the debate. Although 2,500 astronomers from 75 nations attended the conference, only about 300 showed up to vote.

"It's a sloppy definition. It's bad science," he said. "It ain't over."

Under the new rules, two of the three objects that came tantalizingly close to planethood will join Pluto as dwarfs: the asteroid Ceres, which was a planet in the 1800s before it got demoted, and 2003 UB313, an icy object slightly larger than Pluto whose discoverer, Michael Brown of the California Institute of Technology, has nicknamed "Xena." The third object, Pluto's largest moon, Charon, isn't in line for any special designation...

Read the whole article


johng said...

It's probably necessary for teachers and children that the Solar System have a set form. For sometime Pluto has been part of that arrangement.

Yet, through my years of SF reading alone, the planet has always a 'shady' reputation, as if it were an interloper. So this move, right or wrong, is not surprising.

johng said...

Kathryn, Father Oakes at First Things has some musings about Pluto's planetary 'descent' into object status. He quotes this Betrand Russell anecdote about the importance of such rewritings of nature. It's hilarious.

"Bertrand Russell liked to tell the story of the time he gave a lecture after which an elderly lady came up to inform him that the universe actually rested, as the Hindus rightly knew, on the back of a turtle, to which he, in true tortoise mode, snappily replied, “And just what does the turtle rest upon?” to which she (allegedly) said, “Oh sir, you don’t understand, it’s turtles all the way down.”

One of the central debates in philosophy centers on this question: What goes all the way down: numbers or words; the a priori truths of mathematics or the conventions of language?

August is supposed to be, in normal times, a slow month for news. Unfortunately, history is not cooperating, as the headlines testify. But at least we have, for a few days, the diversion of Plutonic nomenclature. And with it the chance to think some Deep Thoughts to get ready for the new school year. Which leaves me with this nagging question: So just what is the difference between a tortoise and a turtle?"