Willson, Robert Wheeler, 1853-1922 · Boston, New York Ginn & company · leaf 175
in several ways: 1. By prolonging the line of sight, if necessary, till it cuts theline of equinoxes on the diagram, and measuring the angle with aprotractor. 162 LABORATORY ASTRONOMY 2. By drawing a line through the sun parallel to the line ofsight, and noting the point where it cuts the graduated… … Fig. 86. Geocentric Longitude Call the reading where the line of sight {from, earth to planet)cuts the circle A, and the other (opposite) reading B. Then the geocentric longitude of the planet is — 90, if A is less than B; and A+B + 90, if A is greater than B. This may be proved by the theorem that…
Astronomy
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