Abstract
Recent Sunspots.—A large group of spots has recently passed across the sun's disc, with the centre of which it was almost coincident on Oct. 11.0. This group, visible for some days to the naked eye, is the largest that has appeared since last December. Its formation was that of a stream or ‘bipolar’ group, and there were appreciable changes from day to day in the appearance of the component spots. The activity of the group was also clearly evident by spectro-scopic observations made at the R6yal Observatory, Greenwich, especially between 9h and 10h G.M.T. on Oct. 6, when the observed radial movements of hydrogen gas, in the form of dark filaments near the leader spot, were of the order of 150 km./sec. A considerable tract of faculse (visible in an ordinary telescope when the spots were near the sun's limb) and of bright hydrogen flocculi (seen at all times on the disc with the spectrohelioscope or on spectroheliograms) accompanied the group, mainly in its rearward portion. Brilliant points or small patches of flocculi of a transient nature were also occasionally seen, in particular one that appeared with the formation of the dark filaments described above. The details of the position of the group are as follows:
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Our Astronomical Column. Nature 126, 625 (1930). https://doi.org/10.1038/126625a0
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DOI: https://doi.org/10.1038/126625a0