Solar Storm Rips Tail Off Comet

posted: 01 October 2007 02:28 pm ET

: This series of four still images were taken from an animation of Comet Encke flying through the solar storm as witnessed by the STEREO satellite. Note Encke's tail being torn off by the coronal mass ejection in the third still above. Credit: NASA

A storm from the sun ripped a tail off a comet, and a NASA satellite captured the whole event.

The spectacular cosmic crash occurred on April 20 when the sun cast out a coronal mass ejection (CME), or large cloud of magnetized gas. The tempest was thrust directly in the path of Comet Encke, which was traveling around the sun, within the orbit of Mercury. As the gas swept over the comet, its tail brightened and then was separated completely from its parent icy rock and carried away.

NASA's pair of Solar Terrestrial Relations Observatory (STEREO) satellites captured the whole incident in newly released images and video.

"We were awestruck when we saw these images," said Angelos Vourlidas of the Naval Research Laboratory. "This is the first time we've witnessed a collision between a coronal mass ejection and a comet, and the surprise of seeing the disconnection of the tail was the icing on the cake."

Comets are icy leftovers from the solar system's formation billions of years ago. They occasionally detour from their home in the cold, distant regions of the solar system, after a gravitational tug from a planet or another comet sends them into the inner solar system.

The sun's heat vaporizes gas and dust from the ice core of the comet, forming its tail.

CMEs are violent eruptions on the sun, with masses upwards of a few billion tons traveling anywhere from 62 to 1,864 miles per second (100 to 3,000 kilometers per second). They can cause geomagnetic storms in the Earth's atmosphere, which can disrupt satellite and radio communications and sometimes disable satellites.

While scientists were aware that a comet's tail would occasionally completely disconnect and suspected CMEs were the culprit, this is the first observation of the violent event.

The NASA observations are detailed in the Oct. 10 issue of Atmospheric Journal Letters.

Another study announced today showed comets can sometimes slow the solar wind down, too.