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What Should Pluto's New Moon Be Named?
New annotated image showing Pluto and moons, including the newly discovered P4, released July 20, 2011.
Credit: NASA, ESA, and M. Showalter (SETI institute)

Planetary scientists have spotted a fifth moon orbiting the dwarf planet Pluto. The petite satellite — it measures just 6 to 15 miles across — showed up in new photos of the Pluto system taken by NASA's Hubble Space Telescope.

This newest member of the solar community currently goes by the unprepossessing label "S/2012 (134340) 1." Clearly, it's in desperate need of a name. What will astronomers christen it?

It can't be named just anything under the sun. As usual with newly discovered astronomical objects, S/2012 (134340) 1's name will be subject to a tough selection process overseen by an organization called the International Astronomical Union. IAU guidelines specify that "objects crossing or approaching the orbit of Neptune … notably [Pluto and its moons], are given mythological names associated with the underworld."

Pluto was the god of the underworld in Roman mythology. Charon, the largest of Pluto's moons, is named after the mythical ferryman who carried the souls of the newly deceased across the River Styx, which separated the world of the living from that of the dead. Nix, Pluto's second-closest moon, was the Greek goddess of darkness and night, and Charon's mother. Hydra, the third closest to Pluto, was a many-headed serpent that guarded a back entrance to the underworld located deep below the surface of a lake. [Why Doesn't Earth's Moon Have a Name?]

The dwarf planet's fifth moon needs a name along these hellish lines, and so does its unnamed fourth moon, which was provisionally designated P4 at the time of its discovery last July. The IAU nomenclature committee will try to honor the wishes of the two moons' discovery team, which includes Alan Stern, a planetary scientist at the Southwest Research Institute in Boulder, Colo.

So, what's his choice? "There are dozens of ideas but nothing is close to settled," Stern told Life's Little Mysteries. He said he prefers to defer the decision until his team finishes mining the Hubble data in search of additional moons orbiting Pluto.

"When we discovered P4, I was on the side of advocating waiting to see if we discovered more moons and then naming them as a group, like we did with Nix and Hydra," Stern said.

If no more moons are spotted, then the two new foundlings will likely be named for an "underworldly" mythological duo. Know any?

This story was provided by Life's Little Mysteries, a sister site to SPACE.com. Follow Natalie Wolchover on Twitter @nattyover. Follow Life's Little Mysteries on Twitter @llmysteries, then join us on Facebook.