You Say Pluto, I Say Pluton

Posted on August 24, 2006

The International Astronomical Union ("IAU") General Assembly has voted to strip Pluto of its designation as a planet because it does not meet the new defining criteria of a planet: that it have sufficient gravity to be a sphere shape and that it be the largest object in its area of space (Pluto is a sphere, but scientists have discovered there are tens of thousands of asteroids that are bigger than Pluto).

Henceforth, Pluto will be known as a dwarf planet, as will Xena and Ceres, which are two more planetary-like bodies in the same part of space as Pluto. So, officially, the Earth has only 8 planets now, not 9. This is upsetting to astrologists and the makers of textbooks, solar system models and solar system placemats, but it's non-negotiable: legally speaking, Pluto is a planet no more.

The IAU has been arguing about the status of Pluto for years: one recent proposal called for Pluto, Xena and Ceres to renamed "plutons." But the astronomers simply hated the name "plutons" and voted for "dwarf planets" instead.

I'd say that the general public is going to be outraged by the news that our solar system has only eight planets now, but recent polls show that more people can name the members of the Three Stooges than the three branches of the U.S. government, so it's unclear how many people can even name the planets in our solar system, much less get riled up about one planet's demotion to dwarf planet status.