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REUTERS
LOS ANGELES, California (Reuters) -- Images snapped by NASA's Cassini spacecraft show that Saturn's moon, Phoebe, is not an asteroid but a 4.5-billion-year-old primordial body from the solar system's outer reaches, scientists said on Wednesday.
The images of Phoebe's pitted surface gave scientists their first close look at a planetesimal, small bodies from an area at the fringe of the solar system known as the Kuiper Belt that may have provided the building blocks of the Milky Way.
High-definition photographs as well as spectrographic and thermal images taken during Cassini's June 11 fly-by revealed that Phoebe likely is made up of ice, rock and carbon compounds similar to those seen in Pluto and Neptune's moon, Triton.
"We believe the solar system was full of Phoebes," scientist Torrence Johnson said at a news briefing at NASA's Jet Propulsion Laboratory in Pasadena, California.
"As the big planets formed, that material was either swept into those planets or swept out of solar system into the Kuiper Belt," Johnson said. "Phoebe apparently stayed behind, trapped in orbit around the young Saturn ... a frozen time capsule waiting for Cassini to open it up."
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