Astronomy for the use of schools and academies (1882) (14577844627)

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:

piter varies from about fiftyseconds to about thirty seconds. His apparent size at hisextreme and mean distances from the earth is shown inFig. 273. Jupiter shines with a brilliant white light, which exceedsthat of every other planet except Venus. The planet is,of course, brightest when near opposition. 251. The Volume and Density of Jupiter. — Jupiter isthe giant planet of our system, his mass largely exceed-ing that of all the other planets combined. His mean 246 ASTRONOMY, diameter is about eighty-five thousand miles; but the equa-torial exceeds the polar diameter by five thousand miles.In volume he exceeds our earth about thirteen hundredtimes, but in mass only about two hundred and thirteentimes. His specific gravity is, therefore, far less than thatof the earth, and even less than that of water. The com-parative size of Jupiter and the earth is shown in Fig. 274. 252. The Sidereal and Synodieal Periods of Jupiter.—It takes Jupiter nearly twelve years to make a sidereal revo-

Text Appearing After Image:

Fig. 274. lution, or a complete revolution around the sun, his orbitalmotion being at the rate of about eight miles a second.His synodieal period, or the time of his passage from oppo-sition to opposition again, is three hundred and ninety-eightdays. 253. The Teleseopie Aspeet of Jupiter. — There are noreally permanent markings on the disk of Jupiter; but hissurface presents a very diversified appearance. The earliertelescopic observers descried dark belts across it, one northof the equator, and the other south of it. With the in-crease of telescopic power, it was seen that these bands PLATE V, ASTRONOMY. 247 were of a more complex structure than had been supposed,and consisted of stratified, cloud-like appearances, varyinggreatly in form and number. These change so rapidly, thatthe face of the planet rarely presents the same appearanceon two successive nights. They are most strongly markedat some distance on each side of the planets equator, andthus appear as two belts under a low

astronomy for the use of schools and academies 1882 book illustrations astronomy images from internet archive library of congress

1882

Library of Congress

http://commons.wikimedia.org/

public domain