Pluto Has Four Moons? Make That Five!

The above image of the Pluto system is one of several taken by the Hubble Space Telescope, using Wide Field Camera 3, in order to confirm the discovery of a fifth moon for Pluto. In the above image the new moon is labeled "P5." Image Credit: NASA, ESA, and M. Showalter (SETI Institute)  

The Pluto system just got bigger!  A team of astronomers using NASA's Hubble Space Telescope have reported the discovery of yet another moon orbiting the icy dwarf planet.

The newly-found moon is estimated to be irregular in shape and 6 to 15 miles across. It follows a 58,000-mile-diameter circular orbit around Pluto that is assumed to be in the same plane as the other satellites in the system.

The Pluto team is fascinated 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 most popular 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 team feels confident that the more they find now, the safer their spacecraft will be when it passes by.

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 and is yet to be named.

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 26th, 27th, and 29th and July 7th and 9th of 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.

To learn more about Pluto and other members of our solar family, visit NASA’s Solar System Exploration site, solarsystem.nasa.gov .

To learn more about the New Horizons mission to Pluto and the Kuiper Belt, visit the mission site, pluto.jhuapl.edu .

To learn more about this and the other discoveries of the Hubble Space Telescope, visit these Hubble sites: hubblesite.org and stsci.edu .

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