Lithographed plate by W H Wesley. These red protuberances on the Sun are normally only visible at totality during a solar eclipse. They can be seen at other times using a spectroscope that is aimed at a tangent to the Sun with its split-jaws partly open. Prominences are masive eruptions of hydrogen gas, often larger than the Earth, which arch away from the surface of the Sun. Asociated with its magnetic field, some violent flares called Coronal Mas Ejection can disrupt the Earth's radio communications and produce spectacular aurora displays. Illustration from 'The sun: its planets and their satellites' by Edward Ledger, published in London in 1882. This was originally published in the 'Memoirs of the Italian Spectroscopical Society'.
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