Solar-filament.gif|thumb|300px|Filaments surrounding a solar flare, caused by the interaction of the plasma in the Sun's atmosphere with its magnetic field. ]] A solar prominence is a large bright feature located in the solar corona. While the corona consists of extremely hot ionized gases, known as plasma, which do not emit much visible light, prominences contain much cooler plasma, similar in composition to that of the chromosphere. A prominence forms over timescales of about a day, and may persist in the corona for several weeks. Many prominences break apart and give rise to coronal mass ejections.

Despite decades of study, the mechanism by which prominences form is not yet well understood. Theories have not satisfactorily explained how prominences can remain stable for such a long time when they are much denser than their surroundings. Magnetic fields are known to be the dominant influence on gas motions within the corona, but the exact form of magnetic interaction required to produce and maintain a large prominence has yet to be determined.

A typical prominence extends over many thousands of kilometres; the largest observed by SOHO was seen in 1997 and was some 350,000 km (216,000 miles) long - some 28 times the radius of the Earth. The mass contained within a prominence is typically of the order of 100 billion tonnes of material.

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