A comet on a near-collision course with the sun and presumed to be doomed to a fiery death surprised astronomers on Thursday when it passed completely through the sun's corona and shot back out into space. Many comets collide with the sun, but they usually burn up as they are little more than rock and ice. In fact, that ice is the reason comets display their trademark tails. As they fly through space, the solar wind blows off tiny bits of the comet.
In comet Lovejoy's case, that trademark tail was one of the things that didn't survive the solar plunge. The temperature of the sun's corona is about three million kelvins, so when Lovejoy was discovered Nov. 27, it was assumed it would make like so many other comets that swoop to close to our nearest star and die a fiery death.
NASA's Solar Dynamics Observatory satellite tracked the comet as it grazed the sun, and some scientists were very excited to see it come out from behind the sun as it continued on its orbit. Lovejoy measures around 660 feet at its core and is classified as a Kreutz class comet because its orbit takes it so close to the sun.
"What an extraordinary 24hrs!," Karl Battams, a solar researcher from the U.S. Naval Research Center, wrote Friday on the Sungrazing Comets blog.
"The result is an almost overwhelming catalog of visual, narrow-band filtered, extreme ultraviolet, and spectroscopic data of a comet experiencing the most extreme environment the solar system has to offer," he wrote.
Lovejoy came within 87,000 miles (140,000 kilometers) of the sun's surface, coming closest at around 7 p.m. EST on Thursday. Coronographs on a handful of solar observatories followed the comet in its historic flight.
"Objects like this can also provide us with a tremendous amount of information about the solar wind and conditions in the solar corona, which in turn allows us to gain more understanding of the Sun as a driver of "Space Weather" at Earth," Battams wrote.