Dwarf planets are crazy

I’m in Hawaii for a few precious nights to point the Keck telescope – one of the largest in the world – at dwarf planet Eris – one of the largest in the solar system. A week ago I would have just said “the largest in the solar system,” but as of last weekend I’m less sure.

The news that Pluto might indeed remain the largest dwarf planet is big, and, even though it will have no impact on the well-settled question of whether Pluto is a planet or not (still: no), it should make fans of the former planet smile a little bit. At least until they remember that Eris is substantially more massive, and in a head-on collision Pluto would suffer the brunt of the damage.