When comet Lovejoy crashed into the sun’s outer atmosphere, known as the corona, and amazingly survived in 2011, researchers used the close encounter to reveal more than we’ve ever known about our star.
“It’s absolutely astounding,” Karl Battams of the Naval Research Lab in Washington, D.C. told NASA in 2011 after Lovejoy escaped the sun’s pull. “I did not think the comet’s icy core was big enough to survive plunging through the several million degree solar corona for close to an hour, but comet Lovejoy is still with us.”
Since the comet was being tracked by five NASA telescopes, researchers were able to plot the course of Lovejoy precisely, and track exactly what forces were working on it. Now, new research, published Friday in Science, explains how this mapping works.
“The comet goes through an area of the solar atmosphere that we can’t really observe,” Dr. Karel Schrijver, one of the authors of the paper told BBC News. “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.”
Scientists were able to track the comet because they knew pretty much when it was going to encounter the sun, so all eyes were trained on it in 2011.
“I’d guess the comet’s core must have been at least 500 meters in diameter; otherwise it couldn’t have survived so much solar heating,” Matthew Knight of the Lowell Observatory and Johns Hopkins Applied Physics Lab told NASA in 2011. “A significant fraction of that mass would have been lost during the encounter. What’s left is probably much smaller than the original comet.”
The big take away from tracking Lovejoy was that its tail danced as it moved past the sun, meaning there were intricacies in the star’s magnetic field that made it zig-zag.
“The tail is not following the comet’s head perfectly as we would expect it to follow… It’s tail gets locked onto the Sun’s magnetic field, and gets flicked back and forth,” Schrijver told the BBC.
By mapping the magnetic field in the sun’s corona in this way, scientists can learn more about what causes solar flares and other “space weather.” Hopefully, with this data, the space weather — and its adverse effects on the Earth, such as radio blackouts — can be easier to predict.
What makes Lovejoy unique as a “sun grazer” comet is its resilience. There have been more than 1,600 sun grazers observed, but most of them don’t actually make it back out the other side and survive the encounter with the sun.
Scientists hope that comet ISON, which will buzz past the Earth later in 2013, will be another sun grazer that survives the encounter, giving researchers even more data.