A new manual of the elements of astronomy, descriptive and mathematical .. (1868)
Kiddle, Henry, 1824-1891 · New York, Ivison, Phinney, Blakeman & co.; Chicago, S.C. Griggs & co. · leaf 82
TWILIGHT. 117. When the sun is a short distance below the horizon,its rays fall on the upper portions of the atmosphere, whichlike a mirror reflect them upon the earth, and thus producethat faint light called twilight The morning twilight isgenerally called the dawn. Fig. 51.H … Let ABC represent three places on the earth, and A H, B IF, C H, theirhorizons respectively. Suppose S to represent the sun, a little below thehorizon, its rays passing through the atmosphere in S C H; at A, no por-tion of the visible atmosphere is illuminated, and consequently there is notwilight;…
Astronomy
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