Double planet frequently been described by many scientists as "double dwarf planets" ("double planets" prior to the 2006 definition of "planet"). The International Astronomical Union (IAU) currently calls Charon a satellite of Pluto, but has explicitly expressed a willingness to reconsider the bodies double dwarf planets at a future time. The Moon-to-Earth mass ratio of 0.01230 (≈ ) is also notably close to 1 when compared to all other satellite-to-planet ratios. Consequently, some scientists view the Earth-Moon system as a double planet as well, though this is a minority view. Eris's lone satellite, Dysnomia, has a radius somewhere around that of Eris;
Dwarf planet history. On March 6, 2015, the "Dawn" spacecraft began to orbit Ceres, becoming the first spacecraft to orbit a dwarf planet. On July 14, 2015, the "New Horizons" space probe flew by Pluto and its five moons. Dawn has also explored the former dwarf planet Vesta. Phoebe has been explored by Cassini (most recently) and Voyager 2, which also explored Triton. These three are thought to be former dwarf planets and therefore their exploration helps in the study of the evolution of dwarf planets. In the immediate aftermath of the IAU definition of dwarf planet, some scientists expressed their disagreement