“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.

New models reveal Pluto and Charon may have spent some of their early history locked together in an embrace after a grazing collision.

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.

Charon is large in size relative to Pluto, and is locked in a tight orbit with the dwarf planet. A new simulation suggests how it ended up there.

The “demoted” dwarf planet Pluto and its largest moon Charon make an unusual pair, and for decades, scientists have been discussing how the binary system—in which each mutually orbits the other—came to be.

Unlike Earth, where the Moon orbits the planet, Pluto and Charon orbit each other, forming a binary system that is more similar to the Earth-moon system than any other moon in the solar system.