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The solar cycle

The solar cycle

A comparison of three images over four years apart illustrates how the level of solar activity has risen from near minimum to near maximum in the Sun’s 11-years solar cycle. These images are captured using He II 304 emissions showing the solar corona at a temperature of about 60,000 degrees K. Many more sunspots, solar flares, and coronal mass ejections occur during the solar maximum. The increase in activity can be seen in the number of white areas, i.e., indicators of strong magnetic intensity.
Courtesy of SOHO consortium. SOHO is a project of international cooperation between ESA and NASA.