Sun-Grazing Comet Flies Deep Into Solar Corona, Adding Fidelity To Existing Solar Magnetic Field Models

On December 15-16, 2011, a Sun-grazing comet, designated Lovejoy (C/2011 W3), passed deep within the hot solar atmosphere – the corona – effectively probing a region that could never be visited by spacecraft because of the intense heat radiating from the nearby solar surface. In a paper published today in the journal Science, researchers from several institutions – including the Solar & Astrophysics Lab at the Lockheed Martin [NYSE: LMT] Advanced Technology Center (ATC) in Palo Alto, Calif. – have analyzed extreme-ultraviolet observations (EUV) from three sun-watching spacecraft and identified characteristics of the embedded magnetic fields through which the comet passed.

“The corona shapes most of the space weather storms that impact Earth,” said Dr. Karel Schrijver of the Lockheed Martin ATC, co-author of the Science paper, and principal investigator of the Atmospheric Imaging Assembly (AIA) onboard NASA’s Solar Dynamics Observatory (SDO). “The only part of the corona that we can study with observatories is the part we can see.

“Comet Lovejoy flew through the corona down to a height of only 10% of the solar diameter, where there is almost nothing that we can image,” continued Schrijver. “It is essentially an ultra high vacuum with a density even lower than where the International Space Station orbits Earth. But when Lovejoy flew through, material from its warming surface evaporated, forming a tail that then lit up brightly enough to be observed. The wiggling of its direction and the changes in intensity and persistence of that tail allowed us to map the otherwise invisible magnetic field.

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