The heavens above: a popular handbook of astronomy (1882)
Gillet, J. A. (Joseph Anthony), 1837-1908 · New York, Chicago, Potter, Ainsworth, & Co. · leaf 209
titudes, there is found to be con-siderable variation in the results obtained. Thus spots near 188 ASTRONOMY. the equator indicate that the sun rotates in about twenty-fivedays; while those in latitude 20°-indicate a period about eighteen hours longer; and thosein latitude 30° aperiod of… … Fig. 203. not only move more rapidly in miles per hour than therest of the solar surface, but they complete the entire rota-tion in shorter time. There appears tobe a peculiar surface-drift in the equatorialregions of the sun,the cause of whichis unknown, but whichgives the _ spots aproper motion;…
Astronomy
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