Discovered in 2000, the reddish, spherical chunk of rock provisionally designated EB173 is a Kuiper Belt object that is either a tiny planet or an asteroid, depending on who you ask. Its orbit puts it between Neptune and Pluto. It's about 600km in diameter, or one-fifth the size of the moon, making it the second largest object of its kind yet discovered in our solar system, just behind the asteroid Ceres.
Four out of five astronomers agree: EB173 needs a sexier name than EB173.