Flammarion, Camille, 1842-1925, Lockyer, Winifred James, Mrs., d. 1879 · New York, C. Scribner & co. · leaf 156
name of umbra; sometimes * This reads strange in 1H70 !—Tr. The Sill 145 at the centre of this part is noticed a more intense dark spot,^Yhieh is called the nucleus. The exterior region of the spothas received the name of penumbra. When it is stated thatthe centre of the spot is black, this… … Fig. 25. A Sun-spot. We may be led to the belief that these spots, generallyinvisible to the naked eye, are insignificant movementscarried on on the Suns surface, and of small extent. It isnot so. They are daily and very important phenomena.Some of them have been known to measure 80,000 miles,that…
Astronomy
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