Pluto was discovered at Lowell Observatory in Flagstaff in 1930. Planet X, as it was called, was quickly renamed Pluto, the ...

but it's three times further from the Sun than Pluto, sitting about 68 AU away. Eris is named after the Greek goddess of discord and strife, and the dwarf planet has one moon, named Dysnomia ...

Nevertheless, because it orbited the Sun like a planet, it was classified as a planet and named Pluto, after the god of outer darkness in Roman mythology. So things stood for 65 years. Although ...