Moonmoon: Also called submoon, or a moon orbiting a moon. New research details if and when one may exist
The planets orbit the Sun, while various moons orbit the planets themselves. Is it possible for a moon to have a satellite of its own? A new research paper has described the circumstances in which this might be possible, but what has caught the fancy of the scientific community — and Internet users — is what to call such a moon of a moon. In their paper on the preprint server arXiv.org, astronomers Juna Kollmeier and Sean Raymond have used the term “submoon”. Other scientists, however, have preferred “moonmoon”.
No moonmoon is known to exist in the Solar System. For one to exist, very special circumstances would need to be place. The host moon needs to have a sufficiently large mass, and the moonmoon must be sufficiently small. Distance too is crucial. The moonmoon needs to be close enough to the moon to be bound by its gravity — but not so close as to be torn apart by tidal forces — and both moons need to be far enough from the planet to prevent the moonmoon from being caught in the planet’s gravity, rather than the moon’s.
