Newcomb, Simon, 1835-1909, Holden, Edward Singleton, 1846-1914, joint author · New York : H. Holt and company · leaf 310
eeks, or months. But so long as they lastthey move regularly from east to west on the suns appar-ent disk, making one complete rotation in about 25 days.This period of 25 days is therefore approximately the rota-tion jjeriod of the sun itself. Spotted Region.—It is found that the spots are chiefly… … Fig. 79.—photograph op the sun. more rare than in latitudes 10° north or south. Connected withthe spots, but lying on or above the solar surface, are faculm, 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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