More 60-Second Space Pluto may not be a full-fledged planet
anymore, but it's got its share of moons. Including a tiny moon
just recently spotted by astronomers. The new addition, which
isn't yet named, brings the dwarf planet's number of known
satellites to four. That's more than Mercury, Venus, Earth and
Mars have combined. Based on Hubble Space Telescope photographs
of Pluto's newfound companion, astronomers estimate the moon to
be just a few dozen kilometers in diameter. Hubble also spotted
Nix and Hydra, two larger moons of Pluto, in 2005. Its largest
moon, Charon, has been known since the 1970s. Pluto's entire
system of moons may have emerged from a protoplanetary smashup
billions of years ago. The new moon turned up during a Hubble
search for a dust ring around Pluto. Such a ring could pose a
hazard to NASA's New Horizons probe, now on its way to Pluto for
a flyby in 2015. So far, the search for any rings has come up
empty. That's good news for fans of Pluto, who are looking
forward to our first close