Neil deGrasse Tyson at the San Francisco Commonwealth Club
Neil deGrasse Tyson, Director of the Hayden Planetarium and popularizer of science, gave a talk Thursday night, 04Feb09, to a sold out audience at the San Francisco Commonwealth Club. The event was filled with a whimsical history of the demotion of Pluto as a planet and addressed many questions from the public in promotion of his recently published book “The Pluto Files“.
Although I am familiar with much of Dr. Tyson’s public work (my favorite of which is “Stupid Design“), I did learn a wealth of information through the course of the evening. Most notably is the fact that back in the 1860s there were 17 planets taught in school textbooks due to the classification of some asteroids as planets, as a result of their, then, recent discovery. In addition, it was highlighted that the California legislature, in an act of bipartisanship, introduced Bill HR 36 in order to “condemn the International Astronomical Union‘s decision to strip Pluto of its planetary status”. A truly fascinating evening.
Tyson tells an entertaining tale, but he is wrong about Pluto’s status. It is not a comet; it is a planet. This is because it is large enough to have attained hydrostatic equilibrium, meaning it has pulled itself into a round shape; its shape is determined by gravity rather than by chemical bonds. That is not true of comets. Since he admits the IAU planet definition is flawed, he should not cite it as vindicating his decision to leave Pluto out of the Rose Center’s display of planets. He is also wrong about Pluto’s popularity being due to the Disney dog. Most who have an affinity for Pluto are people who are already interested in astronomy and the solar system. That includes members of the public.
In short, Pluto hasn’t “fallen,” and such a pronouncement is premature. Even now, there are efforts by both scientists and lay people to overturn the demotion.