Grimthorpe, Edmund Beckett, Baron, 1816-1905 · New York : G.P. Putnam · leaf 243
238 EUiptioal Orbits. not so, except at the two apses. If you look at this figure of an ellipse, you see the motion of the planet … that direction, while the other part is pulling it out of that direction. The sun's force then may be resolved into two forces, one in the tangential direction PT, and the other in the direction TS perpendicular to PT ; and these two forces are proportionate to those two lines. On the other hand,…
Astronomy
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