SOLAR STORM HITS COMET *PIC*

by Kaspel, Saturday, January 08, 2005, 01:48

Battered tail gives visual evidence of solar explosions.

Eruptions of matter from the surface of the Sun can create chaos in a comet's tail, astronomers have found.

They have shown that three different coronal mass ejections in 2002 caused wobbles in the tail of comet Ikeya-Zhang. It is the first time the Sun's ejections have been shown to affect a comet in this way.

Astronomers Geraint Jones of NASA's Jet Propulsion Laboratory, Pasadena, and John Brandt, from the University of New Mexico, Albuquerque, used pictures taken by amateur astronomers at the time of the ejections to examine the tail. They publish their results online in Geophysical Research Letters1.

Jones and Brandt believe that by analysing distortions in the tails of other comets, they will be able to pinpoint exactly where short-lived solar eruptions are coming from, and how far their effects reach into space.

Although several satellites already monitor solar activity in our region of the Solar System, the researchers say that comets could provide useful information about the effects of coronal mass ejections farther away from the Sun.

Gale force

The stream of energetic particles thrown off by the Sun is known as the solar wind, and is responsible for comets' tails. As a comet approaches the Sun, the particles warm up its surface and push a stream of ionized material outwards, forming a distinctive tail that can be 200 million kilometres long.

Solar flares frequently burst from around sunspots, releasing extra energetic particles into the wind. But coronal mass ejections are the most impressive of the Sun's emissions.

These ejections boost the solar wind to gale force, as the star's magnetic field opens up and allows huge amounts of hot plasma to escape into bubbles that are sometimes as large as the Sun itself. If these outbursts reach Earth, they can damage communication satellites and even cause power grids to fail.

Continued:
http://www.nature.com/news/2004/041206/full/041206-4.html