Pluto and Charon are in a region of the outer solar system beyond Neptune called the Kuiper belt, which makes them both rocky and icy. By including these properties in their model, the research team devised a scenario in which the two bodies collided and became ensnared without merging.

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.

Pluto's big moon Charon may have a different origin story than scientists suspected. New research suggests the two bodies engaged in a celestial kiss and tango.