Images: Solar flare heads toward Earth

A solar flare from sunspot 930 (left) sent a giant coronal mass ejection directly toward Earth. The X-Class flare is classified as one of the larger outbursts from the sun and it could cause strong geomagnetic storms. NOAA forecasters estimate a 35 percent chance of more solar flares today. The astronauts on the space shuttle will be safe from the sun's cloud of gas.

Solar flares are tremendous explosions on the surface of the sun that are caused by the sudden release of magnetic energy. Flares can eject solar particles almost to the speed of light, and heat solar material to tens of millions of degrees.

Coronal mass ejections are clouds of electrified, magnetic gas weighing billions of tons. When directed at Earth, the ejections can cause spectacular auroral displays and magnetic storms that occasionally affect satellites, radio communications and power systems.