Astronomy for the use of schools and academies (1882) (14577704529)

Identifier: astronomyforuseo00gill (find matches)
Title: Astronomy for the use of schools and academies
Year: 1882 (1880s)
Authors: Gillet, J. A. (Joseph Anthony), 1837-1908 Rolfe, W. J. (William James), 1827-1910
Subjects: Astronomy
Publisher: New York : Potter, Ainsworth, & Co.
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress



Text Appearing Before Image:
Fig. 327. in a telescope of moderate power, in 1835. This comet appearsto be growing less brilliant. In 1456 it appeared as a cometof great splendor; and coming as it did in a very superstitiousage, soon after the fall of Constantinople, and during the threat- ASTRONOMY. 293 ened invasion of Europe by the Turks, it caused great alarm.Fig. 328 shows the changes undergone by the nucleus of thiscomet during its perihelion passage in 1835. 298. Enckes Comet. — This telescopic comet, two views ofwhich are given in Figs. 329 and 330, appeared in 1818. Enckecomputed its orbit, and found it to lie wholly within the orbitof Jupiter (Fig. 324), and the period to be about three yearsand a third. By comparing the intervals between the succes-
Text Appearing After Image:
Fig. 328. sive returns of this comet, it has been ascertained that itsorbit is continually growing smaller and smaller. To accountfor the retardation of this comet, Olbers announced his cele-brated hypothesis, that the celestial spaces are filled with asubtile resisting medium. This hypothesis was adopted byEncke, and has been accepted by certain other astronomers ;but it has by no means gained universal assent. 299. Biela^s Comet,— This comet appeared in 1826, andwas found to have a period of about six years and two thirds.On its return in 1845, ft met with a singular, and as yet unex- 294 ASTRONOMY.