Eruptive prominence
This sequence of images of the the Sun in the ultraviolet light of a He II emission line at 304 A was taken by Extreme-ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory (SOHO) on Feb. 11, 1996 from its unique vantage point at the "L1" gravity neutral point 1 million miles sunward from the Earth. An "eruptive prominence" or blob of 60,000-degree gas, over 80,000 miles long, was ejected at a speed of at least 15,000 miles per hour. The gaseous blob is shown to the left in each image. These eruptions occur when a significant amount of cool dense plasma or ionized gas escapes from the normally closed, confining, low-level magnetic fields of the Sun's atmosphere to streak out into the interplanetary medium, or heliosphere. Eruptions of this sort can produce major disruptions in the near Earth environment, affecting communications, navigation systems and even power grids. SOHO, with its uninterrupted view of the Sun, can observe such events continually, and allow us for the first time to get a better understanding of how such violent events occur. SOHO is observing these events during the current minimum phase of the sun's 11-year activity cycle.