A short course in astronomy and the use of the globes (1871)
Kiddle, Henry, 1824-1891 · New York, Chicago, Ivison, Blakeman, Taylor & co. · leaf 62
, the revolving body describes a curve, which may either be acircle or an ellipse. 71. The three most important truths pertaining toplanetary motion were discovered by Kepler about theyear 1609 ; and hence are called Keplers Laws. Theyare, 1. The planets orbits are ellipses having the sun orcentral… … 60 ORBITAL REVOLUTIONS 3. The squares of the periodie times of the planets arein proportion to the cubes of their mean distances fromthe sun or central body. By the periodic time of a planet is meant the time which it takesto revolve around the sun. The mean distance is the average dis-tance, found…
Astronomy
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