Monday, February 19, 2007

Coronal Mass Ejection


A Coronal Mass Ejection (CME) blasting off the Sun’s surface in the direction of Earth. In this image, the left portion is composed of an EIT 304 image superimposed on a LASCO C2 coronagraph. Two to four days later, the CME cloud is shown striking and beginning to be mostly deflected around the Earth’s magnetosphere. The blue paths emanating from the Earth’s poles represent some of its magnetic field lines. The magnetic cloud of plasma can extend to 30 million miles wide by the time it reaches earth. These storms, which occur frequently, can disrupt communications and navigational equipment, damage satellites, and even cause blackouts.

The Sun connects with all the planets via the solar wind, a flow of electrically charged particles that constantly 'blows' off the Sun and creates 'space weather'. Space weather interactions can affect and erode the atmospheres of Earth and other planets, and, when channelled through a planetary magnetic field, create beautiful aurorae. Until now, physicists have been principally concerned with the way the solar wind interacts with Earth, the so-called Sun-Earth connection. Now it is time to think bigger.

Credits: ESA/David Hardy

Ulysses has made fundamental contributions to our understanding of the Sun, the heliosphere, and our local interstellar neighbourhood. Charged particles are in fact ‘tied’ by electromagnetic forces and follow the magnetic field lines in space. In the case of the Sun, which is a rotating object, so the field lines are actually twisted into spirals like water from a garden sprinkler.

In mid-December 2006, although very close to the minimum of its 11-year sunspot cycle, the Sun showed that it is still capable of producing a series of remarkably energetic outbursts.

The solar storms, which were confined to the equatorial regions, produced quite intense bursts of particle radiation that were clearly observed by near-Earth satellites. Surprisingly, similar increases in radiation were detected by the instruments on board Ulysses, even though it was three times as far away and almost over the south solar pole. Particle events of this kind were seen during the second polar passes in 2000 and 2001, at solar maximum.

Scientists are busy trying to understand how the charged particles made it all the way to the poles. "Charged particles have to follow magnetic field lines, and the magnetic field pattern of the Sun near solar minimum ought to make it much more difficult for the particles to move in latitude.

Surprises from the Sun’s South Pole from ESA Int 19/02/07
International Heliophysical Year begins from ESA Int 19/02/07
A Year of observing the Sun-Earth relationship Starts PPARC.
The New Solar System from Ryan Wyatt @ Visualising Science.

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