Astronomy for the use of schools and academies (1882)
Gillet, J. A. (Joseph Anthony), 1837-1908, Rolfe, W. J. (William James), 1827-1910 · New York : Potter, Ainsworth, & Co. · leaf 209
Fig. 202. 186. The Proper Motion of the Spots. — When theperiod of the suns rotation is deduced from the motion ofspots in different solar latitudes, there is found to be con-siderable variation in the results obtained. Thus spots near 188 ASTRONOMY. … Fig. 203. the equator indicate that the sun rotates in about twenty-fivedays; while those in latitude 200 indicate a period about eighteen hours longer; and thosein latitude 300 aperiod of twenty-seven days and ahalf. Strictly speak-ing, the sunj as awhole, has no sin-gle period of rota-tion ; but…
Astronomy
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