Last October I wrote about the discovery of two new moons around Pluto. The outer solar system continues to become more interesting, as a group of German astrophysicists report evidence that the “planet” Xena (technically named 2003UB313) is 30% larger than Pluto.

A few weeks ago Laralee and I taught our second-grade science class, and our topic was the solar system. The kids were fascinated to learn that there aren’t just nine planets– that in fact there may be quite a few more. They learned the names of three: Quaoar, Xena, and Sedna. Xena is way out there, taking 560 years to orbit the sun once; Sedna’s highly elliptical orbit is on the order of 10,000 years around.

There’s continuing debate in the astronomic community about whether these new objects can even be called “planets”, and the evidence that Xena is larger than Pluto– and we call Pluto a planet– makes the discussion all the more interesting.

I love this stuff. Indeed, we live in heady times.