for National Geographic News
Our solar system has two new named bodies: Nix and Hydra.
The names were approved last week by the International Astronomical Union, the organization charged with keeping tabs of astronomical nomenclature.
Previously called S/2005 P 2 and S/2005 P 1, the two moons were discovered a year ago in orbit around Pluto.
The discovery of the new bodies was announced on October 31.
"They're the 'Halloween moons' of Pluto," said Alan Stern, a planetary astronomer with the Southwest Research Institute in Boulder, Colorado, whose team made the find.
Stern's team picked the names Nix and Hydraboth figures in Greek mythologyto reflect the underworld theme used in naming objects in the dim reaches of the outer solar system.
But the scientists also wanted them to be special.
The nine members of the discovery team brainstormed about 30 names, Stern said. "Then we wondered what made sense as a pair."
They settled on Nix and Hydra because their initials could stand for New Horizons, the space probe now heading for Pluto, the solar system's last unexplored planet.
(See a virtual solar system.)
The initials seemed particularly appropriate because the astronomers discovered the moons while searching for exploration targets for the New Horizons mission using the Hubble Space Telescope.
There is also a tradition of coding initials into the names of celestial objects, Stern noted.
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