Sharpless, Isaac, 1848-1920, Philips, G. M. (George Morris), 1851-1920, joint author · Philadelphia, J.B. Lippincott company · leaf 256
d how long it willtake to complete it. The period of revolution for thosewhich are determined the most accurately varies fromtwenty-five to one thousand years. So important is themeasurement of double stars considered to be that someobservatories give almost their whole attention to it.In the… … Fig. 55 shows the orbit which one of the compo-nents of y Virginis makes about the other. The num-bers on the diagram indicate the years when the starswere in that relative position. Itwill be noticed that nearly a com-plete revolution has been observed:at one end of the line we have the…
Astronomy
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