The Sun, a roiling ball of plasma, occupies its place in space approximately 93 million miles from Earth. Though it seems simple to inhabitants of this planet -- the Sun shines, giving light and heat -- the processes occurring in the Sun are so complex that many scientists devote their careers to just one aspect of solar activity.

Changes in the activity of the Sun particularly engage solar scientists. Whether fluctuations in the solar magnetic field, expulsions of plasma called coronal mass ejections, emissions of high-energy flares, or changes in the sunspot number, variations in solar activity can be dramatic and therefore highly interesting.

Through careful study of solar activity (particularly sunspots, visible from Earth through telescopes) over hundreds of years, scientists have found a consistent cycle of activity: every eleven years, activity rises to a maximum, then falls to a minimum. To track the solar cycle, scientists plot the average of Wolf numbers (values from a method of counting sunspots devised by Johann Rudolf Wolf in 1848) from various observatories daily to get a sunspot number graph.

The sunspot or solar cycle does not have the same magnitude every eleven years, however. Entire cycles can have lower activity levels than usual, as during the Maunder Minimum from 1645 to 1700, or the upcoming maximum might have more activity than ever. A look at the sunspot plot for the last two centuries will show the fluctuation in minima and maxima.

Solar maximum, the peak of solar activity, occurs, according to the latest predictions, in the year 2000. Scientists expect to see increased activity from sunspots to flares, and the public can expect to see more solar effects at Earth (like magnetic storms and aurora) and more news pieces on the subject over the next few years.

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Posted: 7:59:09 AM  
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