A compendium of astronomy; containing the elements of the science, familiarly explained and illustrated, with the latest discoveries. Adapted to the use of schools and academies, and of the general reader (1850)
Olmsted, Denison, 1791-1859 · New York, R. B. Collins · leaf 134
re 90° from the sun arecalled quadratures ; and the points half way betweenthe syzigies and quadratures are called octants. Thecircle which divides the enlightened from the unen-lightened hemisphere of the moon, is called the circle ofillumination: that which divides the hemisphere thatis turned… … that that half only which is towards the sun can be il-luminated. More or less of this side is turned towardsthe earth, according as the moon is at a greater or lesselongation from the sun. The reason of the differentphases will be best understood from a diagram. There-fore let T (Fig. 31,)…
Astronomy
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