Newcomb, Simon, 1835-1909, Holden, Edward Singleton, 1846-1914, joint author · New York : H. Holt and company · leaf 66
equator. (3). If (5 = 0° (that is, if the star is on the celestial equator), thentan (! = 0, and cos A = 0, A = 90°, 2 ^ = 180°, so that all stars onthe equator are half the time above the horizon, whatever be the lati-tude of the observer. Here we except the pole, where, in this case,tan 9 tan (5… … Fig. 15.—upper and lower Drmi- NAL ARCS. cos A = — tan <5cot l/) tan 6 tan (90° — This shows that when S lies outside the limits + (90° — 0) and_ (90° — ^\ cos Ti will lie without the limits — 1 and + 1, andthere will be no value of h to correspond. Hence, in this case, thestars neither rise nor…
Astronomy
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