Act 1: Pluto, Ceres, Charon, Xena… and the others This A.G. had in fact only one purpose: to determine according to which criteria to include or exclude Pluto from the planetary procession. Until 22nd August, there seemed to be a consensus around two criteria. The planets would be stars: ▶ 1) orbiting a star, but not a star; ▶ 2) sufficiently massive so that the effect of their own gravity (...)