Astronomy for the use of schools and academies (1882) (14577742778)

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. 359- the coma and tail. Now, these three bands are those of cer-tain hydrocarbon vapors: hence it would seem that the comaand tails of comets are composed chiefly of such vapors (315). II. THE ZODIACAL LIGHT. 319. The Geneial Appearance of the Zodiacal Light.—The phenomenon known as the zodiacal light consists of avery faint luminosity, which may be seen rising from thewestern horizon after twilight on any clear winter or springevening, also from the eastern horizon just before daybreakin the summer or autumn. It extends out on each sideof the sun, and lies nearly in the plane of the ecliptic. Itgrows fainter the farther it is from the sun, and can gener-ally be traced to about ninety degrees from that luminary, ASTRONOMY. 319

Text Appearing After Image:

Fig. 360. 320 ASTRONOMY. when it gradually fades away. In a very clear, tropicalatmosphere, it has been traced all the way across theheavens from east to west, thus forming a complete ring.The general appearance of this column of light, as seenin the morning, in the latitude of Europe, is shown inFig. 360. Taking all these appearances together, they indicate thatit is due to a lens-shaped appendage surrounding the sun, and extending a littlebeyond the earthsorbit. It lies nearlyin the plane of theecliptic ; but its exactposition is not easilydetermined. Fig. 361 shows the gen-eral form and posi-tion of this solarappendage, as seenin the west. 320. The Visibilityof the Zodiacal Light.— The reason why thezodiacal light is morefavorably seen in theevening during thewinter and spring than

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1882

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