Sunspot Cycle

Sunspot Cycle

. The location of sunspots (upper panel) and their total area (bottom panel) have varied in an 11-year cycle for the past 100 years, but this activity cycle varies both in cycle length and maximum amplitude. As shown in the upper panel, the sunspots form at about 30 degrees latitude at the beginning of the cycle and then migrate to near the Sun’s equator at the end of the cycle. Such an illustration is sometimes called a “butterfly diagram” because of its resemblance to the wings of a butterfly. The total area of the sunspots (bottom panel), given here as a percent of the visible hemisphere, follows a similar 11-year cycle. (Courtesy of David Hathaway, NASA/MSFC.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University