Pluto's moons named
Hydra and Nix are the names of Pluto's two small moons discovered last year.
June 27, 2006
|June 27, 2006|
Hydra and Nix are the names of Pluto's newfound moons, announced the International Astronomical Union (IAU) June 21. The moons, discovered in May 2005 were previously called S/2005 P1 and S/2005 P2, respectively.
Alan Stern of the Southwest Research Institute and Hal Weaver of the Johns Hopkins University Applied Physics Laboratory co-led the discovery team, which proposed the names. The satellites join Pluto's large moon Charon, discovered in 1978. Hydra and Nix are roughly 5,000 times fainter than Pluto, and they orbit the planet 2 to 3 times as far away as Charon.
A pair of small moons that NASA's Hubble Space Telescope discovered orbiting Pluto now have official names: Nix and Hydra. Photographed by Hubble in 2005, Nix and Hydra are roughly 5,000 times fainter than Pluto and are about two to three times farther from Pluto than its large moon, Charon, which was discovered in 1978.
Photo by NASA/ESA/H. Weaver (JHU/APL)/A. Stern (SwRI)/HST Pluto Companion Search Team
In Greek mythology, Hydra is a nine-headed monster with a snake's body that guards the entrance to Hades, and Nyx is the goddess of night. The names are especially appropriate because Pluto is the ninth planet and named for the god of the underworld. Because asteroid 3908 is already named Nyx, the IAU changed the spelling for Pluto's moon to an Egyptian equivalent, Nix.
"You're going to be hearing a lot more about Nix and Hydra in coming years — astronomers are already applying for telescope time to study their orbits and physical properties. And when New Horizons flies by Pluto in the summer of 2015, each will be mapped in detail," says Stern, also New Horizons' principal investigator.
Each member of the Pluto quadruple system is smaller than the United States. The three moons are shown in the order of their orbits out from Pluto.
Photo by Astronomy: Roen Kelly