Comet Lovejoy flew through the atmosphere of the Sun and somehow managed to survive. In so doing, this visitor from the outer edges of the Solar System revealed previously unknown secrets about the makeup of our local star.
Wave-like formations in the tail were created during the December 15, 2011 close approach, when charged particles were affected by the magnetic field of the Sun. The data collected, some of it from observations made in far-ultraviolet wavelengths, produced a wealth of new data concerning the magnetic field of our local star.
"The comet goes through an area of the solar atmosphere that we can't really observe. We can't go there because our satellites would melt, and we can't see it because there is not much light coming from it. But comet Lovejoy gave us a means to access a part of the solar atmosphere and solar magnetic field that we cannot get into in any other way," Karel Schrijver, of the Lockheed Martin Advanced Technology Center, said.
Hurtling towards its close approach with the Sun at 1,440,000 MPH, the comet was closely watched by a trio of satellites - the Solar Dynamics Observatory, a pair of stereo orbiters, and the Hinode space observatory, built in Japan.
Researchers used a computer model of the Sun to see how predicted obserservations matched against theretical predictions. Doing so, they were able to study how the uneven nature of the Sun's magnetic field behaves.
"The tail is not following the comet's head perfectly as we could expect it to follow. Its tail gets locked onto the sun's magnetic field, and gets flicked back and forth," Schrijver said.
Although Comet Lovejoy unexpectedly survived the close encounter (being the first such comet to do so), it disintegrated two days later. Our new knowledge of the Sun came at the cost of this comet itself.
It is not rare for comets to collide with the Sun - this is seen every few days, on average. What makes this event so rare was the fact that the comet survived its initial passage and reveled so much information about the Sun during its fatal voyage. Astronomers believe the reason Lovejoy was able to survive its passage, at least for a while, was due to its immense size - the comet was estimated at 1,600 feet across, much larger than typical sun-grazing comets.
One of the reasons it is vital to learn the inner workings of the Sun's magnetic field is because flares and solar winds, created in the corona of the Sun, are warped and deflected by this magnetic field. Such outbursts occasionally head to Earth and can cause outages of power systems and artificial satellites.
Comet ISON, which may become the biggest, brightest comet seen in decades, will make its closest approach to the Sun, 680,000 miles away. on November 28.
The new findings were published in the journal Science June 7.
