Collisional family

In astronomy, a collisional family is a group of objects that are thought to have a common origin in an impact (collision). They have similar compositions, and most share similar orbital elements.

Known or suspected collisional families include numerous asteroid families, most of the irregular moons of the outer planets, the Earth and its moon^{[citation needed]}, and the dwarf planets Pluto, Eris, and Haumea and their moons.