August 23, 2007—A rare glimpse of Uranus's "dark side" is hinting at the planet's recent turbulant times, researchers say.
The first image of Uranus snapped by a ground-based telescope—the W.M. Keck Observatory in Hawaii—shows for the first time the dusty rings edge-on to the Earth (bottom), offering a unique view of their dark side.
The solar system's seventh planet was discovered in 1781, but its rings weren't found until 1977. NASA's Voyager 2 spacecraft sent back the first images of the rings in 1986.
A series of previous Keck images (top) shows how astronomers' view of the rings has changed since 2004.
The new image shows that the rings' dust pattern has changed significantly since the 1980s, suggesting that Uranus has suffered occassional large impacts over the past 21 years.
Imke de Pater of the University of California, Berkeley, led a study of the image appearing this week in the online advance edition of the journal Science.
"We think that dusty rings in general are sustained by impacts," de Pater said. "The rings of Jupiter exist because small meteorites continuously bombard the moons in Jupiter's system."
Study co-author Heidi Hammel of the Space Science Institute in Ridgefield, Connecticut, added that Uranus has been "the unappreciated underdog of the outer solar system for too long.
"It is refreshing to see such dynamic change and exciting evolution in the rings and the planet."
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