Why doesn't the IAU call Pluto/Charon a “Binary Dwarf Planet'?

Especially with the discovery of Pluto's fifth moon in 2012, the distant icy planet and its largest moon Charon has gotten a lot of attention. You've undoubtedly heard Pluto referred to as the Pluto-Charon system, or a binary planet system. read more

Pluto and Charon are quite commonly referred to as binary planet system, or a"double planet."As Vincent Maldia points out, the International Astronomical Union (IAU) doesn't classify the Pluto/Charon system this way, but they don't rule it out. read more

In 2006 the International Astronomical Union (IAU) initially considered characterizing Pluto-Charon as a binary planet. But in all their hissy fit fuss over what to call Pluto, Charon was simply left as a satellite of Pluto. read more