S/2004 S 21
= S/2004 S 21
{wiki=S/2004_S_21}
S/2004 S 21 is a natural satellite (moon) of Saturn, discovered in 2004. It is one of the smaller moons of the planet and belongs to a group of moons known as the "irregular satellites," which generally have eccentric orbits and are thought to have been captured by the planet's gravity rather than forming in place.