Planetary Trash Talk

The inspiration for the new NOVA program, "The Pluto Files," featuring astronomer Neil deGrasse Tyson, was the public outcry that accompanied the downgrading of Pluto from a planet to a "dwarf planet" (or "plutoid") by the International Astronomical Union (IAU) in 2006. The scientific debate has raged ever since, and children are among the most vocal defenders of the beleaguered erstwhile planet. Check out this sampling of letters Tyson received from third graders around the country to get a taste for just how impassioned folks can get on this subject.

One little boy wrote in to complain about Pluto's exclusion from the Haydn Planetarium's exhibit of our solar system, helpfully drawing a diagram of Pluto in case the curators needed some guidance. A very literal-minded child worried that "If there are people who live there, they won't exist" if Pluto were no longer a planet. And six-year-old John Glidden argued that he'd taken a poll of 11 of his friends, and they all agreed that Pluto was a planet, so Tyson and his fellow astronomers couldn't possibly be right.

It wasn't just the kids, either. As recently as last year, the Illinois State Senate made March 19 "Pluto Day" throughout the state, in honor of its discoverer, Clyde Tombaugh, and insisted it was still a planet. Ditto for New Mexico's House of Representatives, which voted to recognize Pluto as a planet within state lines, and scientific consensus be damned. And who knows how many relationships have foundered on the question of Pluto's planethood?

In reality, of course, you can't just take a vote to alter scientific reality. The New Mexico House of Representatives can vote to suspend gravity if they like; they'll still go splat if they jump from the top of the state capitol building, all the same. But this is a case of a change in the definition of a planet by a scientific body, and it struck a lot of folks as unnecessary and kind of random.

For the record, here's the current IAU definition of a planet. (1) The object must orbit the sun (check). (2) The object must have enough mass so that it has sufficient gravitational force all by itself to assume a spherical shape (check). And (3) The object must have cleared the area around its orbit. Uh-oh! Therein lies the sticking point. Pluto doesn't meet that criteria.

Surely we can just grandfather Pluto into the solar system, right? We can look the other way! Science doesn't work like that. Bend the rules for Pluto and you've got to do the same for a few other nearby objects, like Ceres, for example. And as Stephen ("Reality has a well-known liberal bias") Colbert makes clear in the clip below, that's a threat against Earth's own special planet-ness.

[conclude]