Abstract
THE appearance this week of a large group of sun-spots serves as a reminder that the sun is still very active though past the peak of the present 11-year sunspot cycle. This sunspot group, in latitude 13° N., crossed the central meridian on August 21·9 and will pass off the western edge of the disk on August 28. The aggregate area of the component spots on August 18 was 1,300 millionths of the sun's visible hemisphere. Since the last note on sunspots (NATURE, July 15, p. 109) a number of fair-sized spots have appeared of area greater than 500 millionths but less than 1,000 millionths. The respective times of central meridian passage (communicated by Greenwich) are as follows: July 17·ld, 17·7d, 20·ld, 23·4d, August 4·3d, 7·3d and 11·1d U.T.
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Recent Sunspot Activity. Nature 144, 362 (1939). https://doi.org/10.1038/144362e0
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DOI: https://doi.org/10.1038/144362e0