Mike Brown has discovered another planet out past Pluto. Unlike Quaoar and Sedna, there is little debate over whether 2003 UB313 is a planet or not, since it’s bigger than pluto, maybe up to twice as big. And 97 times as far from the sun as us, take plenty of thick clothing if you visit.
Another parallel discovery, more interesting to me, is 2003 EL61. This is about a third the mass of Pluto, or roughly the size of Charon – Pluto’s moon – but it has a moon of its own. It’s a tiny thing, roughly 1% of the parent’s mass, and orbits in about 45 days, and is entirely inconsistent with everything that we “know” (ie, knew) about Kuiper Belt Objects.
This is good, because it’s causing some head-scratching amongst the planetologists once more (“dang! we’re going to have to work for our living again”), which hopefully means that they’re learning something. The good (theory) is the enemy of the best.
What would it have been like if our Moon had had a moon? Think of the impact on astronomy and all of the sciences entailed thereby!