Astronomy for the use of schools and academies (1882)
Gillet, J. A. (Joseph Anthony), 1837-1908, Rolfe, W. J. (William James), 1827-1910 · New York : Potter, Ainsworth, & Co. · leaf 314
sehave been observed at sev- eral returns, so that theirperiod has been determinedwith great certainty. In thecase of others the perio-dicity is inferred from thefact that the velocity fellso far short of the paraboliclimit that the comet mustmove in an ellipse. Thenumber of known periodiccomets is… … falls short of it, or exceeds it. Sun Fig. 323. In the case of a few cometsthe observations indi-cate a minute excess ofvelocity : but this cannot{ be confidently asserted.v It is not. therefore, abso-1 lutely certain that anyI known comet revolves! in a hyperbolic orbit:] and thus it is possible,…
Astronomy
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