Newcomb, Simon, 1835-1909, Holden, Edward Singleton, 1846-1914, joint author · New York, H. Holt and Company · leaf 64
ator. (3). If d = 0 (that is, if the star is on the celestial equator), thentan (5 = 0, and cos h = 0,h = 90, 2h = 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 <i> tan (5… … -UPPER AND LOWER DIUR-NAL ARCS. cos h = tan Scot (> tan J tau (90 — 6) This shows that when 6 lies outside the limits -f (90° — 6) and— (90° — ^), cos h 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 sot.…
Astronomy
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