June 7, 2013
Comet Lovejoy’s Close Shave With Sun Provides Scientists With Rare Data
Lee Rannals for redOrbit.com - Your Universe Online
The intrepid comet Lovejoy flew right into the Sun's violent atmosphere and lived to tell scientists the story and help them understand more about our local star.
In December 2011, comet Lovejoy plowed into the Sun's atmosphere, withstanding temperatures that would have obliterated any man-made object. Telescope images taken of the comet's miraculous feat showed how the comet's tail was pulled about by an intense magnetic field. This observation allowed scientists to characterize and report on this force for the first time in the journal Science.
"The comet goes through an area of the solar atmosphere that we can't really observe," said Dr Karel Schrijver of the Lockheed Martin Advanced Technology Center in California. "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."
As the comet hurtled towards the Sun at about 400 miles per second, it showed up as a bright speck followed by a long glowing tail in images provided by NASA's Solar Dynamics Observatory (SDO) and twin Stereo orbiters. These images reveal the comet getting brighter as it entered the solar corona, facing temperatures millions of degrees. As it approached this area, its tail looked as if it was moving.
"The tail is not following the comet's head perfectly as we would expect it to follow," Schrijver said. "It's tail gets locked onto the Sun's magnetic field, and gets flicked back and forth."
The researchers used these observations to find out more about the properties of the Sun's magnetic field. Scientists are currently unable to send a man-made object to the Sun to interplay with its magnetic field in this way, so they were able to utilize the comet and its tail as a proxy. Currently, scientists have to rely on computer models to understand the Sun's atmosphere and its magnetic field, but Lovejoy´s close shave with the scorching stellar body has provided direct data to help improve this process.
When comet Lovejoy made its close approach to the Sun, the scientists were surprised to see that the ball of ice and dust survived.
"There have been about 1,600 Sun-grazing comets observed. But all of them vanished and none came out. It's the first one we have seen that was large enough to survive close passage - although not for very long," Schrijver said.