And speaking of the outer solar system, it seems that Neil deGrasse Tyson isn’t interested in debating whether or not Pluto is a planet.
The planetary scientist in charge of NASA’s New Horizons mission to Pluto and the Kuiper Belt, Alan Stern, issued the debate challenge in an NBC News interview a week ago. As director of New York’s Hayden Planetarium, Tyson left Pluto out of the facility’s main planetary lineup, and wrote a book about the controversy called “The Pluto Files.”
The International Astronomical Union considers Pluto to be a dwarf planet, and not a full-fledged planet, because it has not “cleared the neighborhood around its orbit.” Stern told NBC News last week that Pluto deserved full planetary status, and he wanted to debate the issue with Tyson. “I am challenging him to the equivalent of the ‘Thrilla in Manila,'” Stern said.
I find debates to be poor forums for ascertaining the truth of anything, so I can understand Tyson’s reluctance to engage in them, although I can imagine how frustrating that can be to Pluto’s advocates, since, as a voice of ever increasing fame, Tyson’s articulation of his opinion on the matter reaches far more people than theirs.
I’ve personally never felt much emotion one way or the other on whether Pluto should or shouldn’t be considered a planet. It’s a definitional matter, and as my long time readers probably know, I don’t usually get worked up by definitional matters. I’m more interested in reality, and I’m usually willing to work with whatever definitions someone wants to work with, as long as they stick to them consistently, at least for the duration of our discussion. For example, if you define Pluto as a planet, then you should also favor calling Eris, Makemake, and Haumea planets as well, since they’re similar objects.
Although I do think the “cleared the neighborhood around its orbit” is a terrible, obviously hacked definition to provide the answer the people who came up with it sought. I have some sympathy though. Some of the alternate definitions would have left us with dozens of planets, to the horror of school kids everywhere who would probably have had to memorize all of them.
However, the Pluto debates have been educational. I don’t think many people knew just how small Pluto was (our moon is bigger), or how weird and unplanet like its orbit is. Pluto is a very different type of body from Earth or Mars. Of course, Jupiter and the other gas giants are also very different types of bodies from the rocky inner planets. I sometimes wonder if there shouldn’t be distinct separate names for rocky planets and gas giants. But that would probably just upset people even more than Pluto’s demotion.