Abstract
A Solar Eruption on Nov. 25.—At the meeting of the Royal Astronomical Society on Dec. 12, observations were described of a solar eruption that was seen near the centre of the sun's disc on Nov. 25 with the spectrohelioscope at Greenwich. Eruptive prominences possessing velocities of 100 km./sec. or greater have been often observed in hydrogen light at the sun's limbs with the spectroscope by recording their linear displacements with time. Similarly they are recorded in spectroheliograms in hydrogen or calcium light. The spectrohelioscope in addition enables the observer to follow the changes of the prominences as they are carried by the sun's rotation across the disc as absorption markings. A simple device for progressively changing the wave-length of the light entering the eye enables the observer to locate and measure the line of sight component of the radial velocity outwards or inwards from the sun with which the absorption marking may be moving.
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Our Astronomical Column. Nature 126, 969 (1930). https://doi.org/10.1038/126969a0
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DOI: https://doi.org/10.1038/126969a0