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Asteroid seen in a different light

During this week's close encounter with Earth, astronomers tracked the aircraft-carrier-sized asteroid 2005 YU55 with radar instruments, infrared cameras, visible-light telescopes — and an ultraviolet-sensitive space telescope as well.

This video shows the view from NASA's Swift satellite, which trained its Ultraviolet/Optical Telescope on the space rock as it zoomed away from Earth at 24,300 mph on Wednesday. Swift is best-known for its observations of high-energy outbursts and cosmic explosions, but it turns out that the spacecraft has been involved in 10 asteroid-observing sessions as well.

Swift's scientists had the satellite watch a couple of patches of sky that YU55 was predicted to pass through, and during the second observing opportunity, the telescope got a good fix on the asteroid.

"We observed the asteroid with Swift's Ultraviolet/Optical and X-ray telescopes but, as expected, we saw it only in the UV," Dennis Bodewits, a Swift team member at the University of Maryland in College Park, said in today's video advisory from NASA.

During the 27-minute long exposure, Swift detected short-term variations in brightness caused by the asteroid's rotation.

"The result is a movie of 2005 YU55 at ultraviolet wavelengths unobtainable from ground-based telescopes," NASA reported today. "For planetary scientists, this movie is a treasure trove of data that will help them better understand how this asteroid is put together, information that may help make predictions of its motion more secure for centuries to come."

More about the asteroid encounter:

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