The Grand Daddy of all Prominences Large impressive loop-like structures on the edge of the solar disk sometimes stand out brightly against the dark background of space. Though these structures appear to be very bright and hot, they are actually hundreds of times cooler and denser than the surrounding gases in the sun's corona or outermost atmosphere.
Filaments are dark string-like features that snake across regions of the solar disk.
They are actually prominences that are silhoutted against the much brighter solar surface. Filaments and prominences can remain stable for weeks or even months viewed on the solar disk. Then, without warning, these structures can erupt and blow large amounts of gas out into space. Watch for these features in hydrogen alpha images of the sun. Erupting prominences are closely associated with an important space weather event called a coronal mass ejection.