Solar Cycle

High Quality Content by WIKIPEDIA articles! The solar cycle, or the solar magnetic activity cycle, is the main source of periodic solar variation driving variations in space weather. The cycle is observed by counting the frequency and placement of sunspots visible on the Sun. Powered by a hydromagnetic dynamo process driven by the inductive action of internal solar flows, the solar cycle: * Structures the Sun's atmosphere, corona and wind; * Modulates the solar irradiance; * Modulates the flux of short-wavelength solar radiation, from ultraviolet to X-ray; * Modulates the occurrence frequency of flares, coronal mass ejections, and other geoeffective solar eruptive phenomena; * Indirectly modulates the flux of high-energy galactic cosmic rays entering the solar system.