Astronomy for the use of schools and academies (1882) (14784180953)

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:

ace of Saturn is seen to be diversifiedwith very faint markings ; and, with high telescopic powers,two or more very faint streaks, or belts, may be discernedparallel to its equator. These belts, like those of Jupiter,change their aspect from time to time ; but they are so faintthat the changes cannot be easily followed. It is only on■are occasions that the time of rotation can be determined:rom a study of the markings. 258 ASTRONOMY, 268. Rotation of Saturn. — On the evening of Dec. 7,1876, Professor Hall, who had been observing the satellitesof Saturn with the great Washington telescope (18), saw abrilliant white spot near the equator of the planet. Itseemed as if an immense eruption of incandescent matterhad suddenly burst up from the interior. The spot gradu-ally spread itself out into a long light streak, of which thebrightest point was near the western end. It remained visi-ble until January, when it became faint and ill-defined, andthe planet was lost in the rays of the sun.

Text Appearing After Image:

Fig. 287. From all the observations on this spot, Professor Hallfound the period of Saturn to be ten hours fourteen minutes,reckoning by the brightest part of the streak. Had themiddle of the streak been taken, the time would have beenless, because the bright matter seemed to be carried alongin the direction of the planets rotation. If this motionwas due to a wind, the velocity of the current must havebeen between fifty and a hundred miles an hour. The axisof Saturn is inclined twenty-seven degrees from the per-pendicular to its orbit. ASTRONOMY. 259 269. The Satellites of Saturn. — Saturn is accompaniedby eight moons. Seven of these are shown in Fig. 287.The names of these satellites, in the order of their distancesfrom the planet, are given in the accompanying table : — Distance 1 NAME. fromPlanet in Sidereal Period. Discoverer. Date of Discovery. 9 z Miles. d. h. m. d. I Mimas . . 120,800 0 22 27 0.94 Herschel. . Sept. 17, 1789. 2 Enceladus . 155,000 1 8 53 i-37 Herschel. . Aug

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1882

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