English: These two images, taken a year apart, reveal a moon orbiting the dwarf planet 225088 Gonggong (2007 OR₁₀). Each image, taken by the NASA/ESA Hubble Space Telescope's Wide Field Camera 3, shows the companion in a different orbital position around its parent body. 225088 Gonggong is the third-largest known dwarf planet, behind Pluto and Eris, and the largest unnamed world in the Solar System. The pair is located in the Kuiper Belt, a realm of icy debris left over from the formation of the Solar System. The dwarf planet is about 1520 kilometres across; the moon is estimated to be 240 kilometres to 400 kilometres in diameter. 225088 Gonggong, like Pluto, follows an eccentric orbit, but it is currently three times farther than Pluto is from the Sun. Links: NASA Press Release Hubble Images of 2007 OR10