The shadows do not travel in the same apparent paths as the satellites themselves across the disc, but (in an inverting telescope) below from August to January, and above from February to July.
We come now to the most charming telescopic object in the heavens—the planet Saturn. Inferior only to Jupiter in mass and volume, this planet surpasses him in the magnificence of his system. Seen in a telescope of adequate power, Saturn is an object of surpassing loveliness. He must be an unimaginative man who can see Saturn for the first time in such a telescope, without a feeling of awe and amazement. If there is any object in the heavens—I except not even the Sun—calculated to impress one with a sense of the wisdom and omnipotence of the Creator it is this. "His fashioning hand" is indeed visible throughout space, but in Saturn's system it is most impressively manifest.
Saturn, to be satisfactorily seen, requires a much more powerful telescope than Jupiter. A good 2-inch telescope will do much, however, in exhibiting his rings and belts. I have never seen him satisfactorily myself with such an aperture, but Mr. Grover has not only seen the above-named features, but even a penumbra to the shadow on the rings with a 2-inch telescope.
Saturn revolving round the sun in a long period—nearly thirty years—presents slowly varying changes of appearance (see Plate [7]). At one time the edge of his ring is turned nearly towards the earth; seven or eight years later his rings are as much open as they can ever be; then they gradually close up during a corresponding interval; open out again, exhibiting a different face; and finally close up as first seen. The last epoch of greatest opening occurred in 1856, the next occurs in 1870: the last epoch of disappearance occurred in 1862-63, the next occurs in 1879. The successive views obtained are as in Plate [7] in order from right to left, then back to the right-hand figure (but sloped the other way); inverting the page we have this figure thus sloped, and the following changes are now indicated by the other figures in order back to the first (but sloped the other way and still inverted), thus returning to the right-hand figure as seen without inversion.
The division in the ring can be seen in a good 2-inch aperture in favourable weather. The dark ring requires a good 4-inch and good weather.
Saturn's satellites do not, like Jupiter's, form a system of nearly equal bodies. Titan, the sixth, is probably larger than any of Jupiter's satellites. The eighth also (Japetus) is a large body, probably at least equal to Jupiter's third satellite. But Rhea, Dione, and Tethys are much less conspicuous, and the other three cannot be seen without more powerful telescopes than those we are here dealing with.
So far as my own experience goes, I consider that the five larger satellites may be seen distinctly in good weather with a good 3½-inch aperture. I have never seen them with such an aperture, but I judge from the distinctness with which these satellites may be seen with a 4-inch aperture. Titan is generally to be looked for at a considerable distance from Saturn—always when the ring is widely open. Japetus is to be looked for yet farther from the disc. In fact, when Saturn comes to opposition in perihelion (in winter only this can happen) Japetus may be as far from Saturn as one-third of the apparent diameter of the moon. I believe that under these circumstances, or even under less favourable circumstances, Japetus could be seen with a good opera-glass. So also might Titan.
Transits, eclipses, and occulations of Saturn's satellites can only be seen when the ring is turned nearly edgewise towards the earth. For the orbits of the seven inner satellites lying nearly in the plane of the rings would (if visible throughout their extent) then only appear as straight lines, or as long ellipses cutting the planet's disc.
The belts on Saturn are not very conspicuous. A good 3½-inch is required (so far as my experience extends) to show them satisfactorily.
The rings when turned edgewise either towards the earth or sun, are not visible in ordinary telescopes, neither can they be seen when the earth and sun are on opposite sides of the rings. In powerful telescopes the rings seem never entirely to disappear.