Sunday, March 30, 2008

Wow, Solar Flares!

(Photo by NASA)

A solar flare is a violent explosion in the sun's atmosphere.

Solar flares take place in the outer layers of the sun, (called the corona and chromosphere), heat ing plasma to tens of millions of kelvins and accelerating electrons, protons and heavier ions to near the speed of light. The flares produce electromagnetic radiation across the electromagnetic spectrum at all wavelengths from long-wave radio to the shortest wavelength gamma-rays. Most flares occur in active regions around sunspots, where intense magnetic fields emerge from the Sun's surface into the corona. Flares are powered by the sudden (timescales of minutes to tens of minutes) release of magnetic energy stored in the corona.

X-rays and UV radiation emitted by solar flares can disrupt long-range radio communications and radar on earth.

The frequency of occurrence of solar flares varies, from several per day when the Sun is particularly "active", to less than one each week when the Sun is "quiet". Large flares are less frequent than smaller ones.

The outer most layer of the sun - the corona - is much, much hotter than the inside layers. Group 3 on the Design in Gamma Ray Astronomy course at the University of Southampton in the University of Tenerife, La Laguna, are trying to explain why that is! The reason is thought to be due to micro-flares which differ from normal flares in that they do not eject matter from the sun, but trap the accelerated particles, producing more heat as the particles collide and reactions take place. At the base of the flares, the particles which have been accelerated collide with the plasma and react, producing even more heat.

Group 3 are designing a telescope based on two separate satellites, approximately 400 metres apart, to observe solar flares and solar micro flares. The telescope uses a mask on one satellite to filter photons from the sun and focus them onto a detector on the other satellite. The second satellite uses an 'active' sheild to stop unwanted data from being processed. The shield lets all radiation through, rather than blocking any radiation, but the shield senses what wavelength of photons it is receiving and signals to the detector to ignore the unwanted data.

Group 3: Junayd Miah, Hector Brown, Tony Lap Pang, Illeana Leal and Alba Casado Jon MacRae


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