The
International Astronomical Union has officially christened Pluto's two newest
satellites Nix and Hydra.
The tiny satellites
were discovered by the Hubble Space Telescope last May and are believed to have
been formed from the same giant impact that carved out Charon, Pluto's
third satellite, discovered in 1978.
The names
were proposed this spring by the team that discovered the satellites. Before
the satellites received their official names, the satellites were called P1 and
P2.
In Greek
mythology, Nyx was the goddess of the night and the
mother of Charon, the boatsman
who ferried souls across the River Styx into the underworld ruled by Pluto. The
IAU changed the spelling to "Nix" after the Egyptian spelling of the
goddess to avoid confusion with two asteroids that had already been named
"Nyx."
The
outermost of Pluto's two new satellites is named after Hydra, the nine-headed
mythological serpent that guarded Pluto's realm.
"We
thought it was an appropriately scary image to be the guard at the gate,"
said Alan Stern, an astronomer with the Southwest Research Institute who led
the team that initially discovered the satellites.
In addition
to their relation to Pluto, the names were chosen because their first initials,
"N" and "H," are also the first letters of New Horizons,
the NASA spacecraft launched in January towards the Pluto system. The Hubble
Space Telescope was providing support for the New Horizons mission when it
spotted the tiny satellites.
"The 'P'
and the 'L' in Pluto are in honor of the Percival Lowell, who instigated the
search that resulted in the discovery of Pluto," Stern told SPACE.com.
"The 'N' and the 'H' are exactly parallel to honor New Horizons which
instigated the search that led us to [the new satellites]."
Stern, who leads
the New Horizons mission, also considered the name "Cerberus," the
three-headed hound who also guarded the gates to Hades, but rejected it because
many people associate Pluto with the Disney cartoon character, and having one
object in the system named after a dog was enough.
The new
names were reported yesterday on ScienceNOW.org,
a publication of the American Association for the Advancement of Science. A
formal announcement will be issued Friday, June 23.
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