Saturn's rings

“ The most remarkable characteristic of Saturn, which makes him an object of such interest in the sky, is his possession of a luminous ring. The ring is only luminous on account of its reflection of the sun’s light; hence is invisible to us when, for instance, we are endeavoring to look at the ring from below while the sun is shining above. It also sometimes happens that the plane of the rings passes through the sun or through the center of the earth, in which case only the thin edge of the rings can be seen. ”

“ If a model about a foot in diameter were cut out of tissue paper, the relative proportion of size and thickness would be about right. In space the thickness is very nearly 100 miles, so that, when we look at the ring system edge-on, it becomes all but invisible except in very large telescopes. Clearly a ring so thin cannot be a continuous solid object and recent observations have proved beyond a doubt that Saturn's rings are made up of millions of separate particles moving round the planet, each as if it were an individual satellite. ”

“ Saturn's rings present the only case within the solar system where matter is known to be revolving about a planet at a distance less than Roche's limit, and it is an interesting question whether these rings can remain as a permanent part of the planet's system or are only a temporary feature. ”

“ The mechanical behaviour of a system of rings, on different hypotheses as to their constitution, has been worked out with consummate skill by Clerk Maxwell; who finds that the only possible constitution for Saturn's assemblage of rings is a multitude of discrete particles each pursuing its independent orbit. Saturn's ring is, in fact, a very concentrated zone of minor asteroids, and there is every reason to conclude that the origin of the solar asteroids cannot be very unlike the origin of the Saturnian ones. The nebular hypothesis lends itself readily to both. ”

“ Nothing like them is to be seen elsewhere in the heavens; and when well opened they form, with the globe they inclose, and the retinue of satellites in waiting outside, a strange and wonderful telescopic object. The rings, since they lie in the plane of Saturn’s equator, are inclined 27° to the Saturnian orbit, and 28° to the ecliptic. The earth is, however, comparatively to Saturn, so near the sun, that their variations in aspect, as viewed from it, may in a rough way be considered the same as if seen from the sun. ”

“ We rose still higher. The Sun and its system were rapidly passing. The Earth was but a little spot now; Jupiter himself, that colossal world, had melted away, like Mars and Venus, to a tiny little dot scarcely larger than the Earth. We passed within sight of Saturn, surrounded [21] by his gigantic rings, whose study alone would be sufficient to prove the immense and unimaginable variety reigning in the universe. Saturn is a whole system in itself, with its rings composed of particles torn from it in its dizzy revolution, and with its eight satellites accompanying it like a celestial retinue. ”

“ Outbound and above the ring plane, Voyager 1 gave us this view of Saturn’s rings eight hours after its closest approach to the planet. The unique lighting accentuates the many hundreds of bright and dark ringlets comprising the ring system. The C-Ring (dark gray area) seems to blend into the brighter B-Ring as the concentric features radiate out from the planet. The dark spoke-like features seen in images taken during the approach to Saturn now appear as bright streaks, indicating that they may be composed of small particles. ”

“ The appearance of Saturn is unparalleled in the system of the world; he is surrounded by a ring even brighter than himself, which always remains in the plane of his equator, and viewed with a very good telescope, it is found to consist of two concentric rings, divided by a dark band. By the laws of mechanics, it is impossible that this body can retain its position by the adhesion of its particles alone; it must necessarily revolve with a velocity that will generate a centrifugal force sufficient to balance the attraction of Saturn. ”

“ In all well-directed efforts to explore the more profound secrets of space and of time, it is necessary to be guided by certain conspicuous marks which even unseen planets may leave behind them, on assuming new forms or in closing an inconceivably long term of existence. Within the solar domain there is, perhaps, no object which claims more interest or value for original inquiries in astronomy than Saturn's rings—whether they be regarded as presenting a picture of the first or the last stages of planetary life. ”

“ The present time, when Saturn is the ruling planet of the night, seems favourable for giving a brief account of recent speculations respecting the Saturnian ring-system, especially as the observations of Mr. Trouvelot appear to remove all doubt as to the true nature of the rings, if indeed any doubt could reasonably be entertained after the investigations made by European and American astronomers when the dark inner ring had but recently been recognised. ”

“ It is a singular result of the theory, that the rings could not maintain their stability of rotation if they were everywhere of uniform thickness; for the smallest disturbance would destroy the equilibrium, which would become more and more deranged, till at last they would be precipitated on the surface of the planet. The rings of Saturn must therefore be irregular solids of unequal breadth in the different parts of the circumference, so that their centres of gravity do not coincide with the centres of their figures. ”

“ Sometimes for days together a large part of Saturn must suffer eclipse beneath the encircling rings, but at other times, at night, when the rings are clear of the planet's body, so that the light is not cut off from them, they must appear as radiant arches of glory spanning the sky. ”

“ These charged particles whiz by Titan at a dizzying rate of more than 200 kilometers (120 miles) per second. Titan leaves a motorboat-like wake in its orbital path.
Extending from the orbit of Titan inward to the orbit of Rhea, an enormous cloud of uncharged hydrogen atoms forms a doughnut-shaped torus of ultraviolet-emitting particles. Because of their neutrality, these atoms are not towed around by Saturn’s magnetic field.
Close to the planet, Saturn’s rings act as an effective shield or absorber of charged particles. ”

“ Sometimes we can only see them edgewise, and then even in the largest telescope they are only like a streak of light, and this shows that they cannot be more than fifty or sixty miles in thickness. The one which is nearest to Saturn's surface does not approach him within ten thousand miles. Saturn has no less than ten satellites, in addition to the rings, so that his midnight sky must present a magnificent spectacle. The rings, which do not shine by their own light but by reflected sunlight, are solid enough to throw a shadow on the body of the planet, and themselves receive his shadow. ”

“ Even if all the satellites could be full together, they would not supply a sixteenth part of the light which we receive from our full moon; and they cannot even appear very beautiful when we consider that the apparent brightness of their surface can be but about one-ninetieth of the brightness of our moon's. As for the rings, so far from appearing to be contrived specially for the advantage of Saturnian beings, these rings, if Saturn were inhabited, would be the most mischievous and inconvenient appendages possible. ”

“ Thus turning, it divided into successively formed rings, each of which in time broke up, the matter of the ring gathering into a separate planet. At first this planet, like the original mass, was gaslike, and when separated from the sun it began to gather in on itself, in most cases forming rings, which in time were to alter into the lesser spheres—the moons. The earth and all the planets lying further away from the sun have these little bodies about them, but in one case, as if to show the stages of creation, the unbroken ring remains, forming the magnificent circles which girdle Saturn. ”

“ Saturn has eight moons and is surrounded with the rings which have made it famous from the time the planet was first seen through the telescope. These rings and moons are inhabited by a type of human beings altogether different from those that live on the planet, and are distinctly visible to the dwellers of Saturn by means of powerful telescopes.
The human beings on the rings are not able to watch their neighbors in space, having no instruments to carry their vision beyond the boundaries of their own peculiar abodes. ”

“ When we see Saturn presented as a ball within a ring, or more carefully pictured as a striped globe within a system of rings, we are apt to regard the ideas suggested by such drawings as affording a true estimate of the planet's nature. In fact, many believe that the planet and its rings are really like what is presented in these pictures. It should be understood that what has been actually seen of Saturn by telescopic means cannot, in the nature of things, afford any true picture of the planet and its ring system. ”

“ Reasoning from the most reliable principles of physics, and guided by the light of recent discoveries, many eminent scientists have come to the very just conclusion that the movement in Saturn's rings must be attended with a loss of energy and a reduction in the size of the orbits described by the innumerable disconnected masses of which the curious appendage is now generally believed to be composed. ”

“ If at any time it should disperse, it would either fall into fragments upon the surface of Saturn, or the fragments, mutually coalescing, would form additional satellites to circle round the planet in its path.
To any observer stationed on the planet, between the extremes of lat. 45 degrees on either side of the equator, these wonderful rings would present various strange phenomena. Sometimes they would appear as an illuminated arch, with the shadow of Saturn passing over it like the hour-hand over a dial; at other times they would be like a semi-aureole of light. ”

“ Hence we may imagine some Creations of Stars may move in the Direction of perfect Spheres, all variously inclined, direct and retrograde; others again, as the primary Planets do, in a general Zone or Zodiack, or more properly in the Manner of Saturn's Rings, nay, perhaps Ring within Ring, to a third or fourth Order, as shewn in Plate XXVIII. nothing being more evident, than that if all the Stars we see moved in one vast Ring, like those of Saturn, round any central Body, or Point, the general Phænomena of our Stars would be solved by it ”

“ When the ring appears like a very narrow ellipse, a short time previous to its disappearance, the division, or dark space between the rings, cannot be seen by ordinary instruments.
Sir W. Herschel very properly observes, ‘There is not perhaps another object in the heavens that presents us with such a variety of extraordinary phenomena as the planet Saturn; a magnificent globe, encompassed by a stupendous double ring; attended by seven satellites; ornamented with equatorial belts; compressed at the poles; turning upon its axis; mutually eclipsing its ring and satellites, and eclipsed by them ”

“ The strange problem presented by the rings, which naturally conceal the sun from immense regions of the planet for years together in the very heart of the winter of those regions, is satisfactorily solved when the Saturnian satellites are regarded as the abodes of life, and Saturn himself as the source of a considerable proportion of their heat-supply. We do not say that, in thus exhibiting the Jovian and Saturnian systems in a manner which accords with our ideas respecting the laws of life in the universe, we have given irrefragable testimony in favor of our theory. ”

“ The discovery of the inner or crape ring of Saturn, made simultaneously in 1850 by William C. Bond, at the Harvard observatory, in America, and the Rev. W. R. Dawes in England, was another interesting optical achievement; but our most important advances in knowledge of Saturn's unique system are due to the mathematician. Laplace, like his predecessors, supposed these rings to be solid, and explained their stability as due to certain irregularities of contour which Herschel bad pointed out. ”

“ We have no reason to look upon the rings of Saturn otherwise than as in process of being converted into one or more satellites, most probably more than one; because if the matter they are composed of has been separated from the planet in the form of a sheet, the same as we have seen must have been the case with the matter separated from the original nebula for the planets, the sheet has been already divided into at least three distinct parts, and surely that cannot have been done without some object. ”

“ The three other planets investigated thus far (Venus, Mars, and Mercury) and Earth’s moon have little or no magnetism. Virtually all 22 our knowledge of Saturn’s magnetic environment has been obtained by Pioneer. The spacecraft found rings of particulate material and several small moons near the rings, which strongly affect Saturn’s trapped radiation. These features provide important diagnostic capabilities. A unique finding is the nearly total absence of radiation belt particles at distances closer to the planet than the outer edge of the visible rings. ”