Elements of astronomy ... with explanatory notes, and questions for examination (1855)
Brocklesby, John, 1811-1889 · New York, Farmer, Brace & co. · leaf 276
respective direc-tions are known, about one-half have a retrograde, andthe other a direct motion. 649. Elements—Identity. Three good observa-tions of the right ascension and declination of a comet,together with the times at which they were made, aresufficient to enable the astronomer to calculate… … and from this point it stretches away in two branches BA and BC to aninfinite length, the branches continually diverging from each other. Abody moving along this curve from any point of it can therefore neverreturn to the place whence it started. This curve does not return intoitself. 1. The…
Astronomy
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