You figure it happens a lot, but it's something you never see. Until now.
"Comets are usually too dim to be seen in the glare of the sun's light," says Dean Pesnell at NASA's Goddard Space Flight Center in Greenbelt, Md., who is the project scientist for NASA's Solar Dynamic Observatory (SDO), which snapped images of the comet. "We've been telling people we'd never see one in SDO data."
But an ultra bright comet, from a group known as the Kreutz comets, overturned all preconceived notions. The comet can clearly be viewed moving in over the right side of the sun, disappearing 20 minutes later as it evaporates in the searing heat. The movie is more than just a novelty. As detailed in a paper in Science magazine appearing January 20, 2012, watching the comet's death provides a new way to estimate the comet's size and mass. The comet turns out to be somewhere between 150 to 300 feet long and have about as much mass as an aircraft carrier.
"Of course, it's doing something very different than what aircraft carriers do," says Karel Schrijver, a solar scientist at Lockheed Martin in Palo Alto, Calif., who is the first author on the Science paper and is the principal investigator of the Atmospheric Imaging Assembly instrument on SDO, which recorded the movie. "It was moving along at almost 400 miles per second through the intense heat of the sun -- and was literally being evaporated away."
Typically, comet-watchers see the Kreutz-group comets only through images taken by coronagraphs, a specialized telescope that views the Sun's fainter out atmosphere, or corona, by blocking the direct blinding sunlight with a solid occulting disk. On average a new member of the Kreutz family is discovered every three days, with some of the larger members being observed for some 48 hours or more before disappearing behind the occulting disk, never to be seen again. Such "sun-grazer" comets obviously destruct when they get close to the sun, but the event had never been witnessed.
Which reminds me of the Pink Floyd song, "Set The Controls For The Heart Of The Sun". From their "Ummagumma" album.
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