Another moon for Uranus
By Ron Cowen
Astronomers have confirmed the existence of the 21st moon known to be orbiting Uranus. Dubbed S/2001 U1, the satellite is one of six small Uranian moons that have elliptical orbits and don’t move in the same plane as the planet’s larger moons. Ranging from 10 to 20 kilometers in diameter, these so-called irregular moons seem to have been created by collisions between larger bodies during the formation of the planets.
Because S/2001 U1 is faint and lies at a great distance from Uranus, astronomers had to use several telescopes to confirm its status as a moon.