Fig. 592.—Enlarging ring.
Fig. 593.—Ring shadow.
But the rings are not always so plainly seen as in the foregoing diagram. Sometimes they appear as a mere line of light on each side of the planet, as shown in the margin. This occurs at the time of the equinox (fig. 591). By degrees, however, as they become inclined, they appear broader (fig. 592). The inner ring may be formed of vapour, but the outer ones are of something more solid, as the shadows they cast upon the planet, and it casts upon them, at certain times (figs. 593 and 594).
Saturn possesses eight moons, seven of them revolving in orbits on the plane of the rings, but one is more inclined. These eight satellites have been named as follows:—
| Name. | Distance from Saturn in radii of Saturn. Miles. | Time of Revolution. | Discoverer. |
|---|---|---|---|
| d. h. min. | |||
| 1 Mimas | 3·36 (about) 120,000 | 22 37 | Herschel. |
| 2 Enceladus | 4·30 (about) 150,000 | 1 8 53 | Herschel. |
| 3 Tethys | 5·34 (about) 190,000 | 1 21 18 | Cassini. |
| 4 Dione | 6·84 (about) 240,000 | 2 17 41 | Cassini. |
| 5 Rhea | 9·55 (about) 340,000 | 4 12 25 | Cassini. |
| 6 Titan | 22·15 (about) 790,000 | 15 22 41 | Huyghens. |
| 7 Hyperion | 26·78 (about) 945,000 | 21 7 7 | Lassel and Bond. |
| 8 Iapetus | 64·36 (about) 2,250,000 | 79 0 8 | Cassini. |
Fig. 594.—Ring shadow.
But these eight moons are not so interesting as those belonging to Jupiter, because the great distance they are away precludes much examination of them. They vary much in size, Titan being the largest, and perhaps equal to Mars, Iapetus being next in magnitude. The light of these satellites and the rings is no doubt very great in the aggregate, and must have a magnificent appearance in the heavens (compare page 493). Very likely there are other attendants upon Saturn, but owing to the brilliancy of the rings it is impossible to distinguish them.