The Solar Cycle

Like Earth, the Sun has seasons. More precisely, it has a cycle that lasts about 11 years. In this sequence of images of X-rays from the Sun’s corona, notice how the corona changes from solar maximum (left side) to solar minimum (right side). The bright areas are called active regions, where intense magnetic fields trap hot plasma.

More information: For additional information on current and past solar cycles, try these links.

• Predicted and actual values for the current solar cycle progression from the Space Environment Center in Boulder, CO.
• The Royal Observator in Belgium is home to the World Sunspot Index data center.
• General information on the sunspot cycle as well as a "Sunspots in History" Java applet.