Newcomb, Simon, 1835-1909, Holden, Edward Singleton, 1846-1914, joint author · New York, H. Holt and Company · leaf 308
weeks, or months. But so long as thej lastthey move regularly from east to west on the suns appar-ent disk, making one complete rotation in al)Out 25 days.This j^eriod of 25 days is therefore approximately the rota-tion period of the sun itself. Spotted Region.—It is found that the spots are… … Fig. 79.—photograph of the sun. more rare than in latitudes 10° north or south. Connected withthe spots, but lying on or above the solar surface, are facul{c, mot-tlings of light brighter than the general surface of the sun. Theformation of a sun-spot is said to be often presaged by the ap-pearance…
Astronomy
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