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A prominence is a large, bright, gaseous feature extending outward from the Sun's surface, often in a loop shape. Prominences are anchored to the Sun's surface in the photosphere, and extend outwards into the Sun's 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. The prominence plasma is typically a hundred times cooler and denser than the coronal plasma. A prominence forms over timescales of about a day, and prominences may persist in the corona for several weeks or months. Some prominences break apart and may then give rise to coronal mass ejections. Scientists are currently researching how and why prominences are formed. A prominence forms over timescales of about a day, and stable prominences may persist in the corona for several months, looping hundreds of thousands of miles into space. The red-glowing looped material is plasma, a hot gas composed of electrically charged hydrogen and helium. The prominence plasma flows along a tangled and twisted structure of magnetic fields generated by the sun’s internal dynamo. An erupting prominence occurs when such a structure becomes unstable and bursts outward, releasing the plasma. A typical prominence extends over many thousands of kilometers; the largest on record was estimated at over long – roughly the radius of the Sun. ==Historical== The first detailed description of a solar prominence was in 14th-century Laurentian Codex, describing the Solar eclipse of 1 May 1185. They were described as "flame-like tongues of live embers."〔 See pdf version (here ) (accessed 21 August 2015).〕〔 Original text cited at 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「solar prominence」の詳細全文を読む スポンサード リンク
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