NASA's Hubble Reveals Possible New Moons Around Pluto

October 31, 2005

Dolores Beasley/Erica Hupp
Headquarters, Washington
(Phone: 202/358-1753/1237)

Donna Weaver
Space Telescope Science Institute, Baltimore
(Phone: 410/338-4493)RELEASE: 05-351

NASA'S HUBBLE REVEALS POSSIBLE NEW MOONS AROUND PLUTO

Using NASA's Hubble Space Telescope to view the ninth planet in our
solar system, astronomers discovered Pluto may have not one, but
three moons.

If confirmed, the discovery of the two new moons could offer insights
into the nature and evolution of the Pluto system; Kuiper Belt
Objects with satellite systems; and the early Kuiper Belt. The Kuiper
Belt is a vast region of icy, rocky bodies beyond Neptune's orbit.

"If, as our new Hubble images indicate, Pluto has not one, but two or
three moons, it will become the first body in the Kuiper Belt known
to have more than one satellite," said Hal Weaver of the Johns
Hopkins Applied Physics Laboratory, Laurel, Md. He is co-leader of
the team that made the discovery.

Pluto was discovered in 1930. Charon, Pluto's only confirmed moon, was
discovered by ground-based observers in 1978. The planet resides
about 3 billion miles from the sun in the heart of the Kuiper Belt.

"Our result suggests other bodies in the Kuiper Belt may have more
than one moon. It also means planetary scientists will have to take
these new moons into account when modeling the formation of the Pluto
system," said Alan Stern of the Southwest Research Institute,
Boulder, Colo. Stern was co-leader of the research team.

The candidate moons, provisionally designated S/2005 P1 and S/2005 P2,
were observed approximately 27,000 miles away from Pluto. The objects
are roughly two to three times as far from Pluto as Charon.

The team plans to make follow-up Hubble observations in February to
confirm the newly discovered objects are truly Pluto's moons. Only
after confirmation will the International Astronomical Union consider
names for S/2005 P1 and S/2005 P2.

The Hubble's Advanced Camera for Surveys observed the two new
candidate moons on May 15, 2005. The candidates are roughly 5,000
times fainter than Pluto. Three days later, Hubble looked at Pluto
again. The two objects were still there and appeared to be moving in
orbit around Pluto.

The team looked long and hard for other potential moons around Pluto.
"These Hubble images represent the most sensitive search yet for
objects around Pluto," said team member Andrew Steffl of the
Southwest Research Institute. "It is unlikely that there are any
other moons larger than about 10 miles across in the Pluto system,"
he said.

The Hubble Space Telescope is a project of international cooperation
between NASA and the European Space Agency. The Space Telescope
Science Institute in Baltimore conducts Hubble science operations.
The Institute is operated for NASA by the Association of Universities
for Research in Astronomy, Inc., Washington.

NASA has images from the research available on the Web, at:

http://www.nasa.gov/vision/universe/...ble_pluto.html

For detailed information and images about this research on the Web,
visit:

http://hubblesite.org/news/2005/19

For information about NASA and agency programs on the Web, visit:

http://www.nasa.gov/home


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