Hubble finds Newest Fifth Moon orbiting Pluto

A team of astronomers using  NASA's Hubble Space Telescope  is reporting the
discovery of another  moon orbiting the icy dwarf planet Pluto.  The moon is
estimated to  be irregular  in shape  and 6 to 15  miles across. It is  in a
58,000-mile-diameter  circular  orbit  around  Pluto that  is assumed  to be
co-planar with the other satellites in the system.

"The moons form a series of neatly nested orbits, a bit like Russian dolls,"
said team lead Mark Showalter of the SETI Institute in Mountain View, Calif.
The discovery increases the number  of known moons  orbiting Pluto  to five.
The Pluto team is intrigued that such a small planet can have such a complex
collection of satellites.  The new  discovery provides  additional clues for
unraveling how  the Pluto system formed  and evolved.  The favored theory is
that all the moons are relics of a collision between Pluto and another large
Kuiper belt object billions of years ago.

The  new  detection  will  help  scientists  navigate  NASA's  New  Horizons
spacecraft through the  Pluto system in 2015, when  it makes an historic and
long-awaited high-speed flyby of the distant world.

The team  is using  Hubble's powerful vision  to scour  the Pluto system  to
uncover potential  hazards  to the  New Horizons spacecraft. Moving past the
dwarf planet  at  a speed of  30,000 miles  per hour, New Horizons  could be
destroyed in a collision with even  a BB-shot-size piece  of orbital debris.
"The discovery of so many small moons indirectly tells us that there must be
lots  of small particles lurking unseen  in  the Pluto system,"  said Harold
Weaver of the Johns Hopkins University Applied Physics Laboratory in Laurel,
Md.  "The inventory  of the Pluto system  we're taking  now with Hubble will
help the  New Horizons team design  a safer trajectory  for the spacecraft,"
added Alan Stern  of the Southwest Research Institute in Boulder, Colo., the
mission's principal investigator.

Pluto's largest moon, Charon, was discovered in 1978 in observations made at
the United States Naval Observatory  in Washington, D.C. Hubble observations
in 2006 uncovered two additional small moons, Nix and Hydra. In 2011 another
moon, Kerberos, (old temp name P4), was found in Hubble data.

Styx, temporary name P5, the latest moon  was detected in nine separate sets
of images taken by Hubble's Wide Field Camera 3 on June 26, 27, and 29, 2012
and July 7 and 9, 2012.

In the years following the New Horizons Pluto flyby, astronomers plan to use
the infrared vision  of  Hubble's planned successor, NASA's James Webb Space
Telescope, for follow-up observations.   The Webb telescope will  be able to
measure  the surface chemistry  of  Pluto, its moons, and many  other bodies
that lie in the distant Kuiper Belt along with Pluto.

The Pluto team members are:
M. Showalter (SETI Institute)
H.A. Weaver (Applied Physics Laboratory, Johns Hopkins University)
S.A. Stern, A.J. Steffl, and M.W. Buie (Southwest Research Institute).