Lessons in astronomy including uranography. A brief intoductory course without mathematics (1896)
Young, Charles A. (Charles Augustus), 1834-1908 · Boston, London, Ginn and company · leaf 130
photosphere is Carbon,though this cannot yet be regarded as proved. § 166] SUN SPOTS. 119 166. Sun Spots. — Sun spots, whenever visible, are the mostinteresting and conspicuous objects upon the solar surface.The appearance of a normal sun spot (Fig. 30), fully formedand not yet beginning to break… … Fig. 30. —A Normal Sun Spot (Secchi; modified). which usually are rather hard to see, but sometimes are con-spicuous, as in the figure. Usually, also, within the umbrathere are a number of round and very black spots, sometimescalled vortices, but often referred to as Dawess holes,after the name of…
Astronomy
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