出典:Wiktionary
出典:『Wiktionary』 (2024/11/08 20:29 UTC 版)
double planet (plural double planets)
出典:Wikipedia
出典:『Wikipedia』 (2011/06/22 01:34 UTC 版)
In astronomy, double planet and binary planet are informal terms used to describe a binary system of two astronomical objects that each satisfy the definition of planet and that are near enough to each other to have a significant gravitational effect on each other compared with the effect of the star(s) they orbit. As of 2010, there are no officially classified double planets in our Solar system. One unofficial definition is that the objects orbit a common center of gravity, the barycenter, that is above both their surfaces.