Iapetus, a moon of Saturn, could have its own moon NASA

Stars are orbited by planets, which are orbited by moons, but what comes next? More moons, according to a new analysis.

Juna Kollmeier at Carnegie Observatories in Pasadena, California, and Sean Raymond at the University of Bordeaux, France calculated whether a moon orbiting a planet could have a moon of its own.

A moon of a moon has no formal name, perhaps because we have never spotted one, but both submoon and moonmoon have been suggested.

Such an object would have to be close enough to its host moon …