Pluto: Countdown to the Big Showdown

August 13, 2008

Think of whatever military standoff you can imagine: the Monitor vs. the Merrimac, the Spartans vs.the Persians, Napoleon at Waterloo, the North vs. the South at Gettysburg.

Just 50 miles from Gettysburg, here in the Maryland suburbs at the John Hopkins University's Applied Physics Lab, astronomers are drawing battle lines for a three-day conference entitled: "Great Planet Debate: Science as Process.”

You’ll have the Plutoid Promoters (who want to keep Pluto strictly second-class) vs. the Pluto Huggers (who want to reinstate Pluto's planetary status) duking it out. News stories, TV talk shows, and Internet blogs are building to this event like the lead-up to a prizefight.

For the past two years we’ve been waiting for the other shoe to drop on the hot debate over the status of cold, diminutive Pluto.

In 2006 the International Astronomical Union kicked Pluto out of the exclusive Planet Club and voted that there were only eight serious planets in the solar system. The demotion was decided on a vote by 424 astronomers out of approximately 10,000 professional astronomers around the world.

Why did they go after something that’s been in the astronomy texts for over 70 years?  Because an object even bigger than Pluto had been found in the outer fringes of the solar system. Some astronomers worried that they’d run out of fingers for counting planets if this got out of hand. So, enough was enough.

The public and especially school children, who just love underdog Pluto, decried the decision.   To many planetary astronomers the vote prematurely marginalized the class of objects that dwell in the largest piece of real estate in the solar system, the Kuiper Belt.

Round One in this battle actually started in 2000 when New York City’s American Museum of Natural History (AMNH) decided not to include Pluto in the planets display in its spanking new Rose Center.

Three AMNH staff astronomers thought that time was overdue to retool the solar system and drop Pluto because it lives in the Kuper belt, which is a cluttered and messy place with tens of thousands of sizable icy objects.

They skirted the issue of whether Pluto was truly a planet, it was simply described as a Kuiper belt object (KBO) in the exhibit. The AMNH astromers correctly predicted that larger KBOs would eventually be discovered, and that would make things even more confusing for Pluto's pedigree.

So the AMNH had a defacto solar system display of no more than eight planets. But the unilateral decision to marginalize Pluto like an unwelcomed  relative eventually got noticed by the New York Times.   Pluto's omission ultimately exploded with public derision. If any other museum had done this switcharoo nobody would have cared or paid much attention. But not the venerable AMNH, which historically has been “Astronomy ‘R Us” for the public.

Now we’re at Round Three at tomorrow's APL meeting. The first cannon fire already started on August 12 in a press release launched by Mark Sykes, Director of the Planetary Science Institute.

Sykes isn’t pulling any punches: "The IAU damaged the public perception of science by the high-profile spectacle of imposing, by vote, a controversial definition of a commonly used term. Too often, science is presented as lists of facts to be learned from authority, instead of the dynamic open-ended process that it really is. The IAU reinforced this misconception of science.”

Under a revised planet definition supported by Sykes, he is lobbying for our solar system to have 13 planets. The new members would be Pluto-Charon (a double planet), Eris (which is slightly larger that Pluto), Makemake, and Ceres, the largest member of the asteroid belt and a suspected Kuiper belt refugee.

On Thursday Aug. 14 Sykes will debate with Neil deGrasse Tyson of the AMNH, and host of NOVA Science Now. Since 2001 Tyson has been stoic -- though some might say obstinate -- in standing by the Pluto demotion in the face of withering public ridicule. To Pluto Huggers Neil is the Grinch that refused to add a Pluto ornament in the hallowed planet gallery of the Rose Center.

I’ll be reporting from ringside on Thursday.

Photos, top to bottom: Associated Press; American Museum of Natural History/Rose Center