The Houston Chronicle’s Eric Berger caught up with Neil deGrasse Tyson, the celebrity astrophysicist and media personality recently. Tyson ruminated on a number of subjects, including pizza, Star Wars, and the inability of people to understand the scientific truth behind evolution, GMO foods and, especially, global warming, which he calls “climate change.” But Tyson was quite eloquent about the one thing he is best known for, the downgrading of Pluto from a planet to a “dwarf planet,” which is to say a second-class planet.
In just a few short weeks, the New Horizon space probe is scheduled to fly by Pluto and its system of moons. It has already returned fuzzy but tantalizing images of what was once the ninth planet of the Solar System. The chief investigator of New Horizon, Alan Stern, is a firm supporter of Pluto as a planet and has offered to debate Tyson on the question. Tyson, thus far, has loftily refused, clearly uncomfortable about defending his position against someone with the expertise to dispute it.
Berger asked Tyson if there was anything that New Horizons could discover that would change his mind about Pluto being a planet. Tyson’s answer was lengthy but illuminating.
“Ah, haha. Let me clarify my record on this. I don’t actually have a strong opinion on this. I know it doesn’t seem that way given the way I’ve been caricatured and referenced. I only started calling it a dwarf planet after the official vote was taken in 2006. That’s when ‘dwarf planet’ became the official nomenclature. Before then, here in New York, we simply took Pluto away from the other planets and grouped it with other icy objects in the Kuiper Belt. That’s all we did. It’s more like these guys, than those guys. We didn’t say it was not a planet. We, in fact, don’t count planets. That’s not a particularly scientific exercise, even though it’s a major thing elementary schools do.
“What would we have to find out? Things like, instead of being one-fifth the mass of Earth’s moon, Pluto would be five times the mass of Earth’s moon. But that’s not going to happen. Find out, in fact, Pluto has indeed cleared its orbit of debris, and it owns that zone. But that’s not going to happen either because we already know of 1,000 Kuiper Belt objects out there. We’re not going to undo things we already know about Pluto. So it’s not something I lose sleep over.”
Leaving aside the uncharacteristic modesty concerning Tyson’s role in the downgrading of Pluto, the short answer is: nothing. Tyson has defined, in his own mind, what he believes a planet should be, and Pluto does not fit his definition. The matter, as far as he is concerned, is “settled science” to use an often misused phrase.