Scientists capture collision of a comet and Sun

For the first time, solar physicists at the University of California, Berkeley, have captured the collision of a comet with the Sun

Using instruments aboard NASA's twin STEREO spacecraft, four post-doctoral fellows at UC Berkeley's Space Sciences Laboratory tracked the comet as it approached the Sun and estimate an approximate time and place of impact.

STEREO (Solar Terrestrial Relations Observatory), launched in 2006, consists of identical spacecraft orbiting the Sun, one ahead of Earth and one behind the Earth, providing a stereo view of the Sun. Data from the ground-based Mauna Loa Solar Observatory in Hawaii revealed images of the comet that was on its way to possibly collide with the Sun.

"We believe this is the first time a comet has been tracked in 3D space this low down in the solar corona," said Claire Raftery, a post-doctoral fellow newly arrived from Dublin's Trinity College.

The comet was first discovered after seeing its long, bright tail of dust and ions tagged it as a Sun-grazing comet seen often by solar astronomers and observatories such as STEREO.

Usually comets do not survive because of the Sun's over powering heat but this one apparently did, and disappeared in the chromosphere, evaporating in the 100,000-degree (Kelvin) heat.

Based on the comet's relatively short tail, about 3 million kilometers in length, they believe that it contained heavier elements that do not evaporate readily. This would also explain how it penetrated so deeply into the chromosphere, surviving the strong solar wind as well as the extreme temperatures, before evaporating.

The comet is believed to be Kreutz family of comets, a swarm of Trojan or Greek comets ejected from their orbit in 2004 by Jupiter, and making its first and only loop by the Sun. The swarm probably resulted from the disintegration of a larger comet.

All members of the team study explosive events on the Sun, such as coronal mass ejections, and the hot ionized plasmas they throw into space. Their detour into cometary physics was purely accidental, they said.

"It was supposed to be an exercise, but it took over our lives," Raftery said.