Lessons in astronomy including uranography. A brief intoductory course without mathematics (1896)
Young, Charles A. (Charles Augustus), 1834-1908 · Boston, London, Ginn and company · leaf 348
PA2 and PA3, are ellipses of dif-ferent length, all having S at one of their foci. The first andsmallest of the ellipses is nearly circular, and shaped aboutlike the orbit of Mercury; the next, more eccentric than theorbit of any asteroid; and the third still more so. Now if we … Fig. 101.—Ellipse, Parabola, and Hyperbola. imagine the point F carried farther and farther to the right,the ellipse will grow larger and longer, until when F is infi-nitely far away the curve will become a parabola. Of course if the point F is very distant, even if not infinitelyso, the part of…
Astronomy
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