The Pluto question

Bob Vold has been teaching a freshman astrophotography seminar for years. It’s usually a varied group, as only about half of the astrophotography students are on a trajectory that will take them into a science major.

But each member of this varied group share a common astronomical interest: the fate of Pluto.

There are some strong feelings. Some come down on the side of scientific accuracy, Vold says, and support the 2006 demotion of Pluto to “dwarf planet” status. Others adopt a “once a planet, always a planet” stance.

And Vold himself?

“I think there ought to be a grandfather clause. It’s just sort of common sense,” he said. “Besides, when you tell people that Pluto is a planet—but it’s an exception—they’ll ask what you mean and you can make it a teachable moment.”