A solar cycle refers to the periodic changes in solar activity, primarily the variation in the number of sunspots, solar flares, and solar radiation over an approximately 11-year period. This cycle is associated with the Sun’s magnetic field, which undergoes a complete reversal during each cycle. ### Key Features of the Solar Cycle: 1. **Sunspots**: These are temporary phenomena that appear as dark spots on the Sun's surface, caused by magnetic field fluctuations.
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The solar cycle is the recurrent variation of magnetic activity, with a characteristic sunspot-number period of about eleven years. The large-scale magnetic polarity reverses from one activity cycle to the next, giving an approximately twenty-two-year magnetic cycle. Activity cycles vary in length and amplitude. A satisfactory solar dynamo model must account for polarity reversal, equatorward activity-belt migration in the solar butterfly diagram, the phase relation between polar and active-region fields, and long-term modulation including solar grand minima.