Hubble Discovers New Moon Orbiting Pluto
Pluto may have had its planet status downgraded, but its four known moons have gained a fifth neighbor that NASA scientists discovered using the Hubble Telescope.
The new moon is estimated to be irregular in shape and 6 to 15 miles across, traveling around the icy dwarf planet in a 58,000-mile-diameter circular that is 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 leader Mark Showalter of the SETI Institute in Mountain View, California.
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Hubble spotted the moon, whose short designation is "P5," with one of its wide-field cameras in nine images taken in late June and early July, according to Wired.
P5 is incredibly faint - half as bright as P4, and roughly one one-hundred-thousandth as bright as Pluto - and orbits relatively close to the dwarf planet, reports Scientific American.
The team of scientists studying Pluto were "intrigued" that such a complex collection of satellites orbits such a small planet. The new detection will help scientists navigate NASA's New Horizons spacecraft through the Pluto system in 2015, when it makes its long-awaited high-speed flyby of the distant world.
The discovery could also help scientists understand how Pluto was formed. The leading theory is that the moons surrounding Pluto are left over from a collision between the dwarf planet and another large object from the Kuiper belt - a region of small, icy objects in the outer solar system.
Pluto's largest moon, Charon, was discovered in 1978. Hubble observations in 2006 uncovered two additional small moons, Nix and Hydra, reports BBC News. In 2011, another moon, known as P4, was found by Hubble.
New Horizons, a NASA space probe, is on its way to Pluto and is scheduled to make a high-speed flyby in three years. It will return the first detailed images of the system, whose components are so small and distant that even Hubble can barely see the largest features on the dwarf planet's surface, according to The Los Angeles Times.
"I think there's a very good chance that more Plutonian satellites await discovery," New Horizons principal investigator Alan Stern told Scientific American. "Every time we look we see more. I expect New Horizons will see more that Hubble cannot see."
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