UH astronomersHILO >> Eleven new, small satellites have been discovered spinning around the planet Jupiter, bringing the total to 39, the University of Hawaii Institute for Astronomy announced.
discover 11 moons
A new digital camera gives
astronomers a first
look at the objects
By Rod Thompson
The discoveries were made in December by a team led by Scott Sheppard and David Jewitt of the university and Jan Kleyna of Cambridge University in England.
The discoveries contribute to a complex picture of the area around Jupiter that would be cluttered with objects if not for the vast spaces between them.
A Web site maintained by Jewitt shows an inner area of large moons, including the four discovered by Galileo in 1610. Outside them are much smaller moons circling Jupiter in the same direction the planet spins.
Still further out are more small satellites moving in the opposite direction from the planet's spin. The eleven new moons, all about 1 to 2 miles in diameter, are in this "retrograde" group.
Rounding out the picture are two clusters of objects called Trojans, not circling Jupiter, but flying along in front of and behind the planet, in the same orbit around the sun.
The Trojans are up to 120 miles in diameter, much bigger than the newly discovered satellites.
Astronomers focused on searching for small satellites because a powerful new digital camera called the 12K, placed on the Canada-France-Hawaii Telescope atop Mauna Kea, allows them to see the objects for the first time, Jewitt said.
To find the satellites, the camera took pictures over a period of time, a university statement said. A computer program then searched the pictures to see which objects did not move and must be stars, and which moved and could be satellites.
More studies were needed to separate the satellites from moving specks of light representing asteroids, closer to Earth, the university statement said.
Two theories try to explain how the chunks of rock, barely bigger than Waikiki, came to circle Jupiter.
One says the speeding rocks were caught when slowed by gas around a "bloated" Jupiter during the planet's earliest 1 million years.
Another theory says the satellites clumped together from little lumps of matter around Jupiter.
The four big satellites, all roughly the size of Earth's moon, spin around Jupiter in neat, circular orbits.
The newly discovered satellites move in elongated ellipses at odd angles to each other.
They are also clumped in clusters, suggesting that some were part of bigger satellites that broke apart, the university said.
University of Hawaii UH Institute for Astronomy
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