A text-book of general astronomy : for colleges and scientific schools (1888)
Young, Charles A. (Charles Augustus), 1834-1908 · Boston ; London : Ginn & Company · leaf 81
ted in the figure.Then, if the sun is at£, Fig. 36, it will just have set to an observer at 1,but all the air within his range of vision will still be illuminated. When,by the earths rotation, he has been transported to 2, he will see thetwilight bow rising in the east, a faintly reddish arc… … Fig. 36. —Twilight. tween the light and darkness has become vague and indefinite ; whenhe reaches 4, only a glow remains in the west; and when he comesto 5, night closes in on him. Nothing remains in sight on whichthe sun is shining. 97. Duration of Twilight. — This depends upon the height of the…
Astronomy
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