Nix and Hydra: Naming Two Moons of Pluto
Photographed in May 2005 by NASA’s Hubble Space Telescope, and discovered by research teams in support of theNew Horizons mission, the two moons found orbiting Pluto have been officially named Nix and Hydra by the International Astronomical Union (IAU). They join Pluto’s partner Charon, its largest and closest satellite, which was discovered in 1978.
Nix and Hydra orbit the small planet at about two to three times the distance of Charon, and are approximately 5000 times fainter than Pluto itself.
In accordance with traditional naming guidelines for celestial bodies, both moons were named after characters from stories of ancient mythology. The inner moon, Nix, was named after the Egyptian goddess of darkness and night, and in Greek Mythology is also the mother of Charon. Hydra, a serpent with nine heads, guarded Pluto’s realm in stories from ancient Greek mythology.
The names of the satellites, beginning with N and H, are also intended as an accolade to the New Horizons mission which left Earth on January 19 2006, bound for Pluto, the Kuiper Belt, and beyond. Traveling at 26.67 km/sec, the New Horizons spacecraft is currently 2.1 AU from Earth and 29.29 AU from Pluto. It is expected to reach the distant planet in July 2015, and carries a compact disc containing over 435,000 names of people who signed up to send their names to Pluto.
Lastly, astronomers from around the world eagerly await the IAU verdict on Pluto’s status as a “planet”. The decision will also determine the status of several “Trans Neptunian Objects”, including 2003 UB313 (commonly called Xena), and is expected in late August this year.