Definition of planet In the original draft proposal, an exception was made for Pluto and its largest satellite, Charon, which possess a barycenter outside the volume of either body. The initial proposal classified Pluto–Charon as a double planet, with the two objects orbiting the Sun in tandem. However, the final draft made clear that, even though they are similar in relative size, only Pluto would currently be classified as a dwarf planet. However, some have suggested that the Moon nonetheless deserves to be called a planet. In 1975, Isaac Asimov noted that the timing of the Moon's orbit is in tandem with the
Eris (dwarf planet) retains an oblique reference to Eris's old informal name "Xena", portrayed on TV by Lucy Lawless. In the 2010s, on the heels of the successful Pluto flyby there were multiple studies for follow-on missions to explore the Kuiper belt, and Eris was evaluated among the candidates. It was calculated that a flyby mission to Eris could take 24.66 years using a Jupiter gravity assist, based on launch dates of 3 April 2032 or 7 April 2044. Eris would be 92.03 or 90.19 AU from the Sun when the spacecraft arrives. Eris (dwarf planet) Eris (minor-planet designation 136199 Eris) is the