The elements of theoretical and descriptive astronomy, for the use of colleges and academies (1901)
White, Charles J. (Charles Joyce), 1839-1917 · New York, J. Wiley & sons; · leaf 99
f the northern and the southern summer.The southern summer takes place when the earths distance isonly about ffths of what it is at the time of the northernsummer: hence, the intensity at the former period will be tothat at the latter in the ratio of about (V^)2 to 1, or about ifto 1: in other… … 94 TWILIGHT. TWILIGHT. 101. If the earths atmosphere did not contain particles ofdust and vapor, which serve to reflect the rays of light, thetransition from day to night would be instantaneous, and theintermediate phenomenon of twilight would have no existence. This phenomenonE/^ ^^&jg^^v>…
Astronomy
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