Elements of theoretical and descriptive astronomy, for the use of colleges and academies (1901)
White, Charles J · New York: J. Wiley & sons · leaf 138
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 exact… … Fig. 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, beyond the mean visible border. If,in Fig. 56, ABCD represents the earth, E its centre, and Bthe centre of…
Astronomy
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![An illustration from Nicolai Copernici Torinensis De reuolutionibus orbium coelestium, libri VI : Habes in hoc opere iam recens nato, & aedito, studiose lector, motus stellarum, tam fixarum, quàm erraticarum, cum ex ueteribus, tum etiam ex recentibus obseruationibus restitutos: & nouis insuper ac admirabilibus hypothesibus ornatos. Habes etiam tabulas expeditissimas, ex quibus eosdem ad quoduis tempus quàm facillime caculare poteris. Igitur eme, lege, fruere. [Line in Greek] (1543)](https://img.insideoutlibrary.com/img/200/ia-nicolaicopernici00cope-385-266.webp)
