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Solar Activity

3 September 2014

At www.sciencedaily.com/releases/2014/09/140903104743.htm … an article in the Astrophysical Journal, 2014:792 (1) 'Deciphering Solar Magnetic Activity' – and based on NASA images and data, tells us a little more about how the Sun ticks. Roughly, every 11 years, the Sun switches from a stable and fairly quiet situation into a violently active one, which is the solar maximum. At this time there are numerous sun spots and eruptions of radiation and solar particles that are ejected around the solar system.

The term cycle is somewhat loose as the timing of the solar maximum is not precise. It can be as short as 9 years or as long as 14 years – not quite descriptive of a repetitive cycle (although it is of course repeating itself on a regular basis). Solar scientists have now added a pointer to what might be going on. What are known as 'bright points'  may be the key – small bright spots that also appear to have a cycle. These bright points are composed of extreme ultraviolet and x-ray light and hover around magnetic fields on the Sun, known as g-nodes. This has led to different ideas as to what is going on at the Sun's surface. It appears to be populated with bands of differently polarised magnetic material that move towards the equator from high latitudes. Once the bands from northern and southern hemispheres come close to each other near the equator the different polarities flick off. At this point sun spots begin to grow on the bands and ramp up in intensity. Meanwhile, at high latitudes new bands start up and sun spots at the equator decrease. Hence, it would appear it is the cycle of the bands on their journey towards the equator that drives solar activity. The 11 year cycle becomes the overlap between two much longer cycles.

Needless to say, there is still a mystery. The bands begin life at 55 degrees latitude. Why?

See also www.sciencedaily.com/releases/2014/04/140417191744.htm

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