the.com/binary planets
two worlds so evenly matched neither can call itself the moon.
means a pair of planetary bodies that orbit a shared point in space instead of one circling the other.
from the term borrows from binary stars, where two suns waltz around a mutual center of mass; pluto and charon made the concept famous since charon is so massive the pair's balance point sits outside pluto entirely.
barycenter locationpluto-charon balance point floats in empty space
earth-moon statusclose, but barycenter still lies inside earth
official classificationpluto-charon debated as first known binary planet