Pluto likely acquired large moon Charon in a “kiss and capture” collision billions of years ago. It may have created a subsurface ocean on the icy dwarf planet.

Pluto and its largest moon Charon could have come together via a 10-hour “kiss-and-capture” encounter after a grazing collision

“Because Pluto is rotating rapidly prior to the collision, and because Charon lies mostly outside of their corotation zone, it is able to ‘push’ Charon off, and Charon starts to slowly migrate out,” first author Dr. Adeene Denton, a planetary scientist from the University of Arizona, told The Guardian.