X-Class Flare (1.1 MB)
This animation came the Solar and Heliospheric Observatory (SOHO) spacecraft on April 21, 2002. It shows a full-disk image of the Sun from the Extreme ultraviolet Imaging Telescope (EIT) showing the 'explosion' on the Sun of an X-class flare (the largest class). Courtesy: NASA/ESA

What is a CME? (3.8 Mb)
The largest explosions in the solar system, CMEs launch up to 10 billion tons of ionized gas into space at speeds of one to two million miles an hour. Courtesy: NASA