July 13th, 2012 by James Ayre
A new, fifth moon has been discovered orbiting around the dwarf planet Pluto.
The discovery was made by a team of researchers using the Hubble Space Telescope.
The moon is estimated to be around 6 to 15 miles across, and of an irregular shape. It follows a circular orbit with a 58,000-mile-diameter around Pluto, and is thought 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.
This discovery increases the number of moons that are known to orbit Pluto to five. The researchers are intrigued that such a small planet has such a complex collection of satellites.
The newly discovered P4 and P5 moons provide some clues on how the Pluto system may have formed and evolved. The currently favored theory is that all of Pluto’s moons are relics of a giant collision between Pluto and a large Kuiper belt object billions of years ago.
The discovery should help scientists navigate the New Horizons spacecraft through the Pluto system in 2015. NASA’s New Horizons spacecraft will be the first to do a close 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, P4, was found in Hubble data.”
“Provisionally designated S/2012 (134340) 1, the latest moon was detected in nine separate sets of images taken by Hubble’s Wide Field Camera 3 on June 26, 27, 29, and July 7 and 9.”
“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), and S.A. Stern, A.J. Steffl, and M.W. Buie (Southwest Research Institute).
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.
Image Credits: NASA; ESA; M. Showalter, SETI Institute
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