Astronomy, a handy manual for students and others (1918)
Dyson, Frank Watson, Sir, 1868-1939 · New York, E.P. Dutton & Co. · leaf 62
as it wouldif it were not spinning. Comets. — The ellipse is not the only curve whicha body can describe about another to which it isattracted by a force varying inversely as the squareof the distance. If a cone be cut perpendicularly toits axis, we get a circle; if the plane is not… … PEGTOP. Diag. XXVII. 52 ASTRONOMY is no longer closed, but becomes an open curve calleda parabola, and at still greater divergence of the cut-ting plane from perpendicularity a curve called ahyperbola. The forms of these curves are shown inDiagram XXVIII. All these conic sections are possible paths…
Astronomy
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