The International Astronomical Union has officially approved Kerberos and Styx as the new names for two of Pluto's moons. Image released on July 2, 2013. 
 
 It's official! Two tiny moons orbiting the dwarf planet Pluto finally have new names: Styx and Kerberos. 
 
 The International Astronomical Union — the organization responsible for naming celestial objects — has approved "Kerberos" and "Styx" as the new monikers for two of Pluto's moons that were previously called P4 and P5 respectively, but fans of TV's "Star Trek" might not be too happy about the new names. 
 
 The IAU selected the names based on the results of the Pluto Rocks Internet poll sponsored by SETI (the Search for Extraterrestrial Intelligence), but the top vote-getter, Vulcan, ultimately wasn't chosen as a name for one of the tiny moons. [Photos of Pluto and its Moons] 
 
 Actor William Shatner — who portrayed the Starship Enterprise captain James T. Kirk in the original "Star Trek" TV series — suggested Vulcan (the home planet of the show's pointy-eared Vulcan people) as a possible candidate, and voters overwhelmingly cast their ballots in favor of it. 
 
 In total, nearly 500,000 votes were cast, with about 170,000 of those going to Vulcan alone. In second place was Cerberus with Styx coming in third in the online poll. But for Vulcan, it was not meant to be. 
 
 "The IAU gave serious consideration to this name, which happens to be shared by the Roman god of volcanoes," SETI officials wrote in a statement. "However, because that name has already been used in astronomy, and because the Roman god is not closely associated with Pluto, this proposal was rejected." 
 
 IAU rules states that Pluto's moons should be named for mythological characters of the underworld in Greek and Roman mythology. Pluto is known as the ruler of the underworld in ancient mythos. 
 
 Cerberus, the three-headed dog in Roman mythology, came in a clear second in the Pluto Rocks ballot with nearly 100,000 votes, but IAU officials decided to tweak the name slightly, instead opting to name the moon Kerberos — Cerberus' equivalent in Greek myth. 
 
 The name Styx, the river that separates the living from the dead in ancient myth, garnered about 88,000 votes for a third place finish. 
 
 Pluto, the most famous dwarf planet in our solar system, underwent a well-publicized (and somewhat controversial) reclassification that took away its title as the ninth and most distant planet from the sun. So, how well do you know this fascinating world? Start the Quiz 0 of 10 questions complete 
 
 Pluto Quiz: How Well Do You Know the Dwarf Planet? Pluto, the most famous dwarf planet in our solar system, underwent a well-publicized (and somewhat controversial) reclassification that took away its title as the ninth and most distant planet from the sun. So, how well do you know this fascinating world? 0 of questions complete 
 
 Scientists used the Hubble Space Telescope to discover Styx around Pluto in 2012. The space telescope also helped researchers discover the existence of Kerberos in 2011. Both moons are about 15 to 20 miles (20 to 30 kilometers) in diameter. 
 
 In all, five moons are known to be orbiting Pluto. Charon, the largest moon, was first spotted in 1978. Two more moons, Nix and Hydra, were discovered by Hubble in 2005. 
 
 Scientists will get a close-up view of the two new moons and the rest of the Pluto system in 2015 when NASA's New Horizons spacecraft flies by. Bound for Pluto, the probe, launched in 2007, will search for additional moons that Hubble is unable to detect and travel to the Kuiper Belt, a mass of icy bodies left over from the early formation of the solar system. 
 
 Editor's Note: This story was updated at 12:25 p.m. EDT (1625 GMT) to correct an error. NASA's New Horizons spacecraft was launched in 2006 and will fly by the Pluto system in 2015. 
 
 Follow Miriam Kramer on Twitter and Google+. Follow us on Twitter, Facebook and Google+. Original article on SPACE.com. ||||| Formerly known as P4 and P5, Pluto’s tiniest moons now have official names: Kerberos and Styx. 
 
 The names were among the top three selected by voters during a two-week polling period; they have just been approved by the International Astronomical Union’s official nomenclature committee. 
 
 Thus, from this day forward, the two tiniest of rocks orbiting the overgrown-snowball-formerly-known-as-a-planet will conjure the tales of a three-headed dog guarding the gates of the underworld (Kerberos), and the river that doomed souls must cross (Styx). 
 
 “I hope the public is going to be pleased with the decisions that were made,” said Mark Showalter, the SETI Institute scientist who discovered P4 in 2011 and P5 in 2012. “I don’t think anybody’s ever tried quite the scale of an Internet poll as we did.” 
 
 “What? That’s impossible! I’m going to lead a revolt” — William Shatner 
 
 Normally, whoever discovers a new celestial body gets a crack at naming it. But Showalter and his colleagues decided to take a more populist approach: They offered the public a chance to christen the new moons. 
 
 For two weeks in February, anyone with a computer could vote for their favorite names, or suggest ideas of their own. The caveats: Names needed to represent characters bearing more than just a passing relation to Pluto, the Greek god of the underworld, and must not have already been bestowed upon a celestial solar system object. 
 
 Initially, there were 12 names on the ballot, including such minions of Hades as Eurydice, Alecto, and Persephone. After a few days, Showalter added eight more. By the time voting closed, more than 450,000 votes had been cast, and voters had written in with 30,000 other options (including Stephen and Colbert, Mickey and Minnie, Potato and Pota(h)to, and various siblings claimed to be underworldly). 
 
 Among those write-ins was Vulcan, the Roman god of fire and volcanic fury, and the first addition to the ballot. Suggested on February 12 in a tweet by the actor William Shatner, Vulcan quickly zoomed ahead of the competition, leading the final tally with more than 170,00 votes. 
 
 Showalter submitted Vulcan, and second-place Cerberus (99,432 votes) to the International Astronomical Union for approval. 
 
 But when mulling over the names, the IAU found there were already too many objects named after Vulcan – not including the fictional home world of Star Trek‘s Mr. Spock – and after much deliberation, ruled that Vulcan wouldn’t work. 
 
 “What? That’s impossible! I’m going to lead a revolt,” Shatner said, when Wired told him of the outcome. “Pluto is so big and cold that it deserved to have a hot little rock running around it, named Vulcan — for fire.” 
 
 Cerberus, too, ran into trouble – it was also already in use, by an asteroid. Instead, Showalter and colleagues tried Kerberos, the Greek spelling. And in place of Vulcan, they submitted third-place Styx (87,858 votes), which in addition to being a river, is also the name of the goddess of unbreakable oaths. 
 
 The IAU approved both. 
 
 “It’s a disappointment of mine that Vulcan wasn’t approved by the IAU, but there were so many issues around it having to do with its prior use,” Showalter said, noting that “Vulcan” is the name of a hypothetical inner solar system planet, as well as a class of sun-grazing asteroids. 
 
 The decision doesn’t rule out the possibility of something named after Vulcan in the Pluto system, however. 
 
 When the New Horizons spacecraft flies near the five-mooned world in 2015, it’ll be busy snapping photos of Pluto and its largest satellite, Charon. The images should return incredibly detailed views of these far-off iceballs, pictures that will allow scientists – and the rest of us – to discern surface features like craters and mountains. Unlike orbiting bodies, these features aren’t subject to many nomenclature restrictions (which leads to such awesomeness as Mount Doom on Titan and various artists on Mercury). 
 
 Right now, New Horizons is still 6 astronomical units away from Pluto, and the planetary runt is still just a bright point of light. By April 2015, the spacecraft will be close enough to the distant, icy world that its onboard cameras should produce images exceeding the resolution of the best Hubble Space Telescope images. 
 
 Maybe, hiding somewhere in those pixels, is a kick-ass ice volcano that could only be called Vulcan, an erupting fountain of fury that wouldn’t be the same by any other name. ||||| Sorry, William Shatner. The International Astronomical Union decided not to name either of Pluto’s two smallest moons after Mr. Spock’s home planet of Vulcan, despite an online campaign that garnered global support for the “Star Trek” star’s suggestion. 
 
 Vulcan was the top vote-getter during a “Pluto Rocks” contest to come up with official names for the moons previously known as P4 and P5. According to results released by election organizer Mark Showalter, a planetary astronomer with the SETI Institute, Vulcan blew away the competition with 174,062 votes from people all over the world. 
 
 Coming in a distant second with 99,432 votes was Cerberus, the Roman name for the three-headed dog that guards the entrance to the underworld in classical mythology. Third place went to Styx, the Greek name for the river separating Earth from the underworld, with 87,858 votes. 
 
 “They didn't name the moon Vulcan. I'm sad.” Shatner tweeted Tuesday morning after the IAU announced its decision. (In an earlier tweet, he noted that “Vulcan won in a landslide.”) 
 
 Instead, the IAU -- which describes itself as “the internationally recognized authority for assigning designations to celestial bodies and surface features on them” -- went with Kerberos for P4 and Styx for P5. Kerberos is the Greek version of Cerberus; the name was changed “to avoid confusion with an asteroid called 1865 Cerberus,” the IAU explained in Tuesday’s announcement. 
 
 Moons of the solar system 
 
 Cerberus and Styx were leading the contest until Shatner suggested Vulcan in a Feb. 12 tweet. He also proposed the name Romulus, in honor of the home planet of the Star Trek beings known as Romulans. But that never even made it to the online ballot, because the solar system already has a moon named Romulus -- it orbits the asteroid Sylvia, along with another moon called Remus. 
 
 What about Vulcan? This was tricky too, because the name had already been used to describe a planet once thought the orbit even closer to the sun than Mercury. The hypothetical planet never materialized, but the name stuck. 
 
 “Although this planet was found not to exist, the term ‘vulcanoid’ remains attached to any asteroid existing inside the orbit of Mercury, and the name Vulcan could not be accepted for one of Pluto’s satellites,” the IAU said. 
 
 Shatner wasn’t having it. 
 
 “So they name a moon Kerebus because there's already a Cerebus asteroid but a mythological planet knocks out Vulcan?” he tweeted. 
 
 Later, Shatner accused the powers-that-be of being partial to "Star Wars": “Where's Fisher?!!! She's been too quiet lately.” 
 
 That was followed by: “Star Trek fans have had it rough. First JJ blows up Vulcan and now SETI finds a loophole to deny it from coming back!” (Actually, Capt. Kirk, it was the IAU’s decision. SETI only ran the online election.) 
 
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 The IAU noted another problem with Vulcan. Pluto is the Greek name for the ruler of the underworld -- he was the brother of Zeus, ruler of the heavens, and Poseidon, ruler of the seas -- and Pluto’s other three moons have underworld-themed names too. There’s Charon, who ferries souls of the dead across the rivers Styx and Acheron; Nix, goddess of the night and mother of Charon; and Hydra, the nine-headed monster who served as guardian of the underworld. Vulcan would have been an outlier. 
 
 “Vulcan does not fit into the underworld mythological scheme,” the IAU announcement said. 
 
 Kerberos and Styx were discovered in 2011 and 2012, respectively. They appeared in images of the Pluto system taken by the Hubble Space Telescope in preparation for the 2015 visit by NASA’s New Horizons spacecraft. New Horizons is more than halfway to the dwarf planet. After its rendezvous with Pluto, it will travel to the Kuiper Belt, the source of many of the solar system’s comets. 
 
 In a Google+ hangout, SETI’s Showalter suggested that New Horizons may find a crater in the Pluto system worthy of naming after Capt. Kirk, Mr. Spock or other "Star Trek" characters. 
 
 Shatner was not appeased. “Did you hear the consolation?” he tweeted. “They may name a crater after Kirk. A pockmark on a planetoid is a fitting tribute? (Rolling my eyes).” 
 
 Return to Science Now. ||||| Star Trek fans have had it rough. First JJ blows up Vulcan and now SETI finds a loophole to deny it from coming back!
– Though Star Trek fans (led by William Shatner) overwhelmingly won an online vote to name one of Pluto's recently found moons "Vulcan" earlier this year, the International Astronomical Union has decided against the moniker. It has named the former planet's fourth and fifth moons "Styx" and "Kerberos," instead, Space.com reports. "The IAU gave serious consideration to this name, which happens to be shared by the Roman god of volcanoes," says the poll's sponsor, SETI. "However, because that name has already been used in astronomy, and because the Roman god is not closely associated with Pluto, this proposal was rejected." (The IAU had specified that Pluto's moons had to be named after underworld figures from classical mythology.) Kerberos is the Greek equivalent of Cerberus, the three-headed dog who guarded the underworld's entrance; it was the second-place winner in the poll, with 100,000 votes to Vulcan's 170,000. Styx, which scored 88,000 votes, is a mythological river that separates the living from the dead. Shatner is not happy with the decision, reports Wired. "Star Trek fans have had it rough. First JJ blows up Vulcan and now SETI finds a loophole to deny it from coming back!" he wrote on Twitter, adding, "Who'd ever thought I'd be betrayed by geeks and nerds?" As a consolation, a rep from SETI says it may name a crater after Captain Kirk, the LA Times reports.