The elements of theoretical and descriptive astronomy, for the use of colleges and academies (1872)
White, Charles J. (Charles Joyce), 1839-1917 · Philadelphia, Claxton, Remsen & Haffelfinger · leaf 137
se which we see in the moon, with a radius nearly fourtimes that of the moon, and a surface about thirteen times thatof the moon. 145. Librations.—By libration is meant an apparent oscilla-tory movement of the moon, which enables us, in the course ofits revolution, to see something more than an… … l Pig. 56, earth to that of the moon does not always intersect the surfaceof the moon at the .same point, and we are able at times to look 132 OTHER PERTURBATIONS. a few degrees, east or west, b?yond the mean visible border. If,in Fig. 56, ABCD represents the earth, E its centre, and Rthe centre of…
Astronomy
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