Hubble finds 10th planet slightly larger than Pluto
In 2005, Hubble captured an image of a 10th planet that has been nicknamed Xena. The plutoid, as trans-Neptunian dwarf planets are called in the Kuiper Belt, has an extremely reflective surface possibly caused by methane frost. The IAU has yet to rule on Xena's official name or its status. But its discovery confirms one thing about Pluto and its neighbors — we still have much to learn about them.