Pluto, the icy dwarf planet has five known moons. According to International Astronomical Union (IAU) rules, Pluto’s natural satellites are named for characters associated with the underworld of Greek and Roman mythology. The Plutonian system is highly compact. The Plutonian satellite system was created by a massive collision. The five discovered satellites orbit within the 3% of the region. In order of distance from Pluto, they are Charon, Styx, Nix, Kerberos, and Hydra.

Charon, the largest of the five moons. It is as big as Pluto. It was discovered by James Christy on June 22, 1978. It is mutually tidally locked with Pluto, so they are together considered as “double dwarf planet”. It is so close to Pluto that it only takes about six days to orbit Pluto. Theories suggest that Pluto has nearly ten moons and one or more ring systems but the brightness of Pluto and Charon make the other moons appear dim.

In May 2005, the Hubble Space Telescope discovered two more moons, named Nix alongside with its tiny moon Hydra. They were discovered by Max Mutchler and Andres Steffl. The name “Nix” comes from the Greek goddess of darkness and night. They are both in the range of 20 – 70 miles in diameter. Nix follows a circular orbit in the same plane as Charon. Its orbital period is 24.9 days. Nix is fainter than Hydra. NASA’s New Horizons spacecraft will image the Pluto system when it finally arrives there in 2015.

Styx is the fifth confirmed natural satellite orbiting Pluto whose discovery was announced on July 11, 2012. Styx is estimated to have a diameter of between 6 and 16 miles and orbital period of 20.2 days. It is irregular in shape. It is formed from the debris which was the result of the collision. Kerberos is a small natural satellite of Pluto whose existence was announced on July 20, 2011. It is in the range of 8 – 21 miles in diameter. Kerberos is located between the orbits of Nix and Hydra. Kerberos was discovered on June 28, 2011. Its brightness is only about 10% of that of Nix.