A comet’s close encounter with the Sun has given scientists a look at a solar region that has never been visited by spacecraft.
In 2011, comet Lovejoy hurtled deep into the Sun’s violent atmosphere – an area called the solar corona.
Telescope images have revealed how the comet’s tail was pulled about by an intense magnetic field, allowing scientists to characterise this force for the first time.
Dr Karel Schrijver, from the Lockheed Martin Advanced Technology Center in California, said: “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.”
Comet Lovejoy, which is named after the Australian astronomer who discovered it, ploughed into the Sun’s atmosphere on 15 December 2011.
With an advance knowledge of its orbit, scientists were able to capture the event with trained Nasa’s Solar Dynamics Observatory and twin Stereo orbiters, as well as Japan’s Hinode spacecraft.
Hurtling towards the Sun at 600km (400 miles) a second, the comet appears as a fast-moving, bright speck followed by a long glowing tail.
The images reveal the comet becoming increasingly bright as it entered the solar corona, where it encounters temperatures of millions of degrees Celsius. The tail also began to move.
Dr Schrijver explains: “The tail is not following the comet’s head perfectly as we would expect it to follow. Its tail gets locked onto the Sun’s magnetic field, and gets flicked back and forth.”
By studying the comet’s movements, the researchers were able to find out more about the properties of the magnetic field for the first time. This, they said, was key.
The Sun’s magnetic field drives the strong solar winds and explosions that occur in the solar corona. These violent events can blast out particles into space and cause “space weather” which can damage satellites and telecommunications infrastructure.
Currently, scientists are using computer models to try and understand the Sun’s atmosphere and its magnetic field, but said that the data from comet Lovejoy would help them to improve this process.
After comet Lovejoy made its close approach, the scientists were surprised to see that the ball of ice and dust survived, re-emerging on the other side of the Sun. Two days later, though, it disintegrated.
Solar physicists are hoping for another attempt to capture the movements of another Sun-skimming comet later in 2013.
Source: science mag