Tuesday, December 20, 2011

Comet Stays Alive After Buzzing Sun


Much to everyone’s surprise, comet Lovejoy survived its heated encounter with the sun late yesterday.
Between the hours of 7 and 8 p.m. ET, cameras aboard NASA’s sun-watching satellite the Solar Dynamics Observatory (SDO) had a ringside seat to the bombing of the bun, and they managed to lock onto the comet.
Nasa satellite images show comet Lovejoy racing through the superheated solar corona, shedding material. Credit: NASA/SDO

SDO’s onboard cameras provided live views that were streamed over the Internet, showing the comet’s precarious journey directly through the million-degree heat of the solar corona. All the while Lovejoy was visibly shedding material as it reached an altitude of only 87,000 miles from the sun’s surface.
While most watching the solar spectacle, including astronomers, thought Lovejoy would completely dissipate due to the intense solar baking, the plucky comet amazingly emerged on the far side of the sun a short time later—shining nearly as bright as it did before its close encounter.
However, after having barnstormed the sun, the latest analyses of the images show that, even though the singed comet appears to have survived, it’s not without wounds. The comet’s tail—composed of dust and gas shed from the vaporizing core—has been lost. Remnants of the tail appear to be visible in images along the track the inbound comet took before reaching the sun.
The comet's tail and detached head are seen on opposite sides of the sun. Credit: NASA/SOHO
Now, having survived, the severed head of the comet, less than a day after grazing the sun is already showing evidence of growing a new tail.
With at least five spacecraft trained on the fiery event these past days, astronomers hope to learn a lot more not only about Lovejoy and other sungrazer comets but also about how the sun works and its impact on Earth.
Karl Bottoms, of Naval Research Lab in Washington D.C., said on his Sungrazing comet website today, “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 (it’s one of the reasons my group is interested in sungrazing comets).”
Now that the main event is over, the race is on to see if anyone can pick up comet Lovejoy through ground-based telescopes as it departs the sun along its 400-year orbit. Bets are that it will take at least two to five days looking for the comet in the morning sky just before sunrise.
But after seeing how comet Lovejoy has fooled astronomers already, who knows what this little comet has in store for observers.

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