Elementary astronomy; a beginner's text-book (1899)
Holden, Edward Singleton, 1846-1914 · New York, H. Holt and company · leaf 218
bit of Mars is very nearly a circle and the oval of thisfigure has been exaggerated purposely. The curve that Marsdescribes is not exactly circular, but it is much less oval thanFig. 127. MOTIONS OF THE PLANETS—KEPLERS LA WS. 197 a curve the orbit of Mars really was. It was not a circleat any rate.… … Fig 128.—An Ellipse. An ellipse is a curve such that the siwi of the distancesof every point of the curve from two fixed points {the foci)is a constant quantity. The student should draw a number of ellipses for practice. Drivetwo tacks into a board at S and S. Tie a string at S and the otherend of…
Astronomy
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