Abstract
THE March issue of Shy and Telescope contains a brief notice of solar spicules, which are very small spike-like prominences most commonly seen in the polar regions of the sun. They have previously been seen during solar eclipses; but the coronagraph makes it possible to carry out daily observations of their numbers and duration. Dr. Walter O. Roberts is in charge of the observations made at Harvard College Observatory's Fremont Pass station at Climax, Colorado, and he has found that the spicules last only four or five minutes from the time of detection until they fade out completely. A spicule is brightest just before it attains its full height, and after reaching its maximum elongation it begins to fade out without any perceptible motion. Their average, width is about 4,500 miles and most of them are only a few thousand miles high. The largest spicule sometimes lasts eleven minutes, and some of the smaller ones about two minutes. At times as many as twenty-five spicules have been seen simultaneously in a 60° arc of the sun's polar limb. They are not seen in disturbed regions of the sun, and they show material flowing outward from the lower layers of the atmosphere; this is in contrast to the ordinary solar prominences, which show material when it is falling inward to the sun's surface.
Article PDF
Rights and permissions
About this article
Cite this article
Spicules on the Sun. Nature 156, 362 (1945). https://doi.org/10.1038/156362b0
Issue Date:
DOI: https://doi.org/10.1038/156362b0