© NASA/Swift/Univ. of Leicester/Bodewits et al.This image of Comet Lulin taken Jan. 28 merges data acquired by Swift's Ultraviolet/Optical Telescope (blue and green) and X-Ray Telescope (red). At the time of the observation, the comet was 99.5 million miles from Earth and 115.3 million miles from the sun.
While waiting for high-energy outbursts and cosmic explosions, NASA's Swift Gamma-ray Explorer satellite is monitoring Comet Lulin as it closes on Earth. For the first time, astronomers are seeing simultaneous ultraviolet and X-ray images of a comet.
"We won't be able to send a space probe to Comet Lulin, but Swift is giving us some of the information we would get from just such a mission," said Jenny Carter, at the University of Leicester, U.K., who is leading the study.
"The comet is releasing a great amount of gas, which makes it an ideal target for X-ray observations," said Andrew Read, also at Leicester.
A comet is a clump of frozen gases mixed with dust. These "dirty snowballs" cast off gas and dust whenever they venture near the sun. Comet Lulin, which is formally known as C/2007 N3, was discovered last year by astronomers at Taiwan's Lulin Observatory. The comet is now faintly visible from a dark site. Lulin will pass closest to Earth -- 38 million miles, or about 160 times farther than the moon -- late on the evening of Feb. 23 for North America.
