Elements of astronomy ..with explanatory notes, and questions for examination . e of the ring is ex-actly coincident with the plane of the planets equator andis inclined to the ecliptic at an angle of 28° 10/ 27. Give an account of the discovery of Saturns ring 1 What is said respecting its formand constitution ? What of its rotation, position, and inclination ? PHASES OF THE RING. 249 581. Phases of the King. When viewed througha telescope at considerable intervals of time the ring ofSaturn presents different aspects. For at one time itappears broad and flat and of an elliptical shape, with a
Elements of astronomy ..with explanatory notes, and questions for examination . e of the ring is ex-actly coincident with the plane of the planets equator andis inclined to the ecliptic at an angle of 28° 10/ 27. Give an account of the discovery of Saturns ring 1 What is said respecting its formand constitution ? What of its rotation, position, and inclination ? PHASES OF THE RING. 249 581. Phases of the King. When viewed througha telescope at considerable intervals of time the ring ofSaturn presents different aspects. For at one time itappears broad and flat and of an elliptical shape, with anopen space between it and the planet, while at anotherit is narrowed down and looks like two handles project-ing from each side of the planet; and then again it van-ishes entirely from our sight. 582. The causes of these changes are found in the fol-lowing facts; First, that the ring, like the earths axis,always remains parallel to itself, and Secondly, that weview it in different positions at different times. 583. This subject is illustrated in Fig. 76, where the FIG, SATURN AND HIS RING. curve abed, represents the orbit of the earth, the centralfigure the sun and A, B, C, D, E, F, Grf H, eight positionsof Saturn in his orbit. Now if we were stationed uponthe sun, Saturn being at 0, the solar light falling uponthe flat surface of the ring would be reflected back tous, and we should see the ring in its greatest breadth ; theopening between the planet and the ring, would likewisebe readily discerned. But as the planet in its orbitualmotion advanced to D, the visible portion of the ringwould contract, since we should now view its surfacemore obliquely than we did at first. 584. When Saturn had arrived at E, where the planeof the ring passes through the sun, the solar rays wouldfall only on the edges of the ring, which is so thin thatthe reflected light would be too faint to render it visible, Describe the phases of the ring ? Illustrate by the aid of figure 76, 250 SOLAR S
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Keywords: ., bookcentury1800, bookdecade1850, bookidelem, booksubjectastronomy
