Pluto is a Planet, Redux

Looking at my first blog posts has a certain charm to it.  One of the first posts on this blog that ever drove a significant amount of traffic was a post about the decision to demote Pluto as a planet at the IAU conference in 2006.

Pluto is a Planet

Scientific American has a nice article out on revisiting that debate, and the options that will be present at a conference on the topic this summer.  An except:

Pluto lovers, don’t despair: Researchers have not given up the fight for the former ninth planet. Many of them put up a fuss two years ago when the International Astronomical Union (IAU) downgraded Pluto to the status of mere dwarf planet. Now they plan to revive the debate, this time under the banner of public understanding of science.

Researchers on both sides of the issue are set to gather in August at Johns Hopkins University Applied Physics Laboratory in Laurel, Md., for what’s being called “The Great Planet Debate: Science as Process.” The goal, says the conference’s co-organizer Mark Sykes, director of the Planetary Science Institute in Tucson, Ariz., is to teach the public that science is a process of constant revision and refinement. “People should be exposed to that process,” he says. “The IAU process gave the impression that science is done by a bunch of scientists voting behind closed doors.”

In my original coverage, I posted this simple snippet on the Pluto Vote Revolt.   It received thousands of page views in a matter of days:

Pluto Vote Revolt!

In the end, I still agree largely with the comments from the NASA lead on the New Horizons project:

Dr Alan Stern, who leads the US space agency’s New Horizons mission to Pluto and did not vote in Prague, told BBC News: “It’s an awful definition; it’s sloppy science and it would never pass peer review – for two reasons.

Pluto discoverer Clyde Tombaugh pictured in 1980 (AP)

Pluto was discovered in 1930 by the American Clyde Tombaugh

“Firstly, it is impossible and contrived to put a dividing line between dwarf planets and planets. It’s as if we declared people not people for some arbitrary reason, like ‘they tend to live in groups’.

“Secondly, the actual definition is even worse, because it’s inconsistent.”

One of the three criteria for planethood states that a planet must have “cleared the neighbourhood around its orbit”. The largest objects in the Solar System will either collect together material in their path or fling it out of the way with a gravitational swipe.

Pluto was disqualified because its highly elliptical orbit overlaps with that of Neptune.

But Dr Stern pointed out that Earth, Mars, Jupiter and Neptune have also not fully cleared their orbital zones. Earth orbits with 10,000 near-Earth asteroids. Jupiter, meanwhile, is accompanied by 100,000 Trojan asteroids on its orbital path.

These rocks are all essentially chunks of rubble left over from the formation of the Solar System more than four billion years ago.

“If Neptune had cleared its zone, Pluto wouldn’t be there,” he added.

Stern said like-minded astronomers had begun a petition to get Pluto reinstated. Car bumper stickers compelling motorists to “Honk if Pluto is still a planet” have gone on sale over the internet and e-mails circulating about the decision have been describing the IAU as the “Irrelevant Astronomical Union”.

Let’s hope that saner minds prevail, and that the fact that Pluto was “temporarily” demoted from planetary status becomes a piece of arcane trivial from the early 21st century.

One thought on “Pluto is a Planet, Redux

  1. You’re right on the money! Stern was accurate in saying the IAU vote was hijacked. Interestingly, only four percent of the IAU voted, most of whom were not planetary scientists. No absentee voting was allowed, meaning one had to be in the room to vote. 424 out of 10,000 IAU member actually voted.

    As a writer and blogger who has extensively written and advocated for the overturning of this ridiculous demotion, I applaud your statement and am thrilled to hear that so many people visited your site on the Pluto Vote Revolt. You should consider attending the conference, as it is open to the public. I definitely plan on going.

    Here’s to reinstating Pluto as a planet in 2009!

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