Chicago Tribune Editorial - In defense of Pluto

Chicago Tribune Editorial - In defense of Pluto
Copyright © 2006, Chicago Tribune
Published August 15, 2006

The international community is split down the middle on a controversy central to our times. This has nothing to do with the future of the Middle East, stem cell research or global warming. The question confronting 2,500 astronomers from 75 countries in Prague this month is whether Pluto should be stripped of its planethood.

You remember Pluto, the ninth planet from the sun. It's a plucky little ball of ice out there in the far reaches of the solar system.

Truth be told, Pluto has never quite fit in with the other planets. It's smaller than our moon, is solid where other outer planets like Jupiter are giant and gaseous, and it travels a wacky, elliptical orbit. But Pluto's been an official planet in good solar system standing since Clyde Tombaugh discovered it 76 years ago.

The debate over Pluto's fate has heated up again because astronomers a year ago discovered another object orbiting the sun in similar wacky fashion, an object that is larger than Pluto. Both Pluto and the newest discovery are in the Kuiper Belt, a vast ring of icy objects beyond Neptune that orbits the sun. The newcomer is still officially known as 2003UB313, although its discoverers nicknamed it "Xena" after the mythic warrior princess from the 1990s TV series of that name.

The International Astronomical Union is determined to put an end to this ongoing debate about planethood at its meeting in Prague. Astronomers believe they can do this by officially defining what the heck a planet is. Surprisingly, this has never been done. If the astronomers had spelled it out 76 years ago, we might not be in this pickle because Pluto might never have passed the bar. But here we are in 2006 with no way to define a planet and, frankly, we've grown quite fond of Pluto, wacky orbit and all.

Rumors are that the IAU might try to come up with a ranking system. There would be the terrestrial planets (Mercury, Venus, Earth, Mars). There would be the giants (Jupiter, Saturn, Uranus and Neptune). Then there would be the dwarfs, or the Trans-Neptunian Objects (TNOs) or the minor planets.

Prior to last summer, this would have been a category of one: Pluto.

If the scientists in Prague really think this asterisking of Pluto is going to pass muster with the world's Plutophiles, they've been staring into their telescopes too long. Defenders of Pluto know an "also-ran" category when they see it and they won't stand for it.

Pluto is a planet. Period. And as long as Pluto is a planet, then shouldn't Xena be invited into planethood? The answer to that is yes. The solar system should officially expand to 10 planets. There's nothing sacred about the number nine. Before Clyde found Pluto, there were only eight. So now there will be 10.

There's your definition, astronomers. No rankings necessary. If you're bigger than Pluto, you're a planet. The Big 10. Has a nice ring to it.