Large Eruptive Prominence Imaged by STEREO.

What's happened to our Sun? Last week, it produced one of the largest eruptive prominences ever seen. Pictured above , the prominence erupted in only a few hours and was captured in movie form by NASA's twin Sun-orbiting STEREO satellites. A quiescent solar prominence is a cloud of hot solar gas held above the Sun's surface by the Sun's magnetic field . Unpredictably, however, prominences may erupt, expelling hot gas into the Solar System via a Coronal Mass Ejection (CME). As pictured above, many Earths would easily fit under the expanding ribbon of hot gas. Although somehow related to the Sun's changing magnetic field , the energy mechanism that creates and sustains a Solar prominence is still a topic of research .