An international team of astronomers has announced the discovery of a new moon of Uranus, boosting the planet's tally of orbiting satellites to 21.

The U.S. space agency's Jet Propulsion Laboratory in Pasadena, California, says 11 astronomers collaborated in discovering the moon, which is about 10 to 20 kilometers across and circles Uranus in an irregular, eccentric orbit.

The moons of Uranus take their names from characters in the works of William Shakespeare and Alexander Pope, but the new moon has not yet been officially named.