The god or time; sign [Symbol], his scythe.
MEAN DISTANCE FROM THE SUN, 881,000,000 MILES. DIAMETER, POLAR,
66,500 MILES; EQUATORIAL, 73,300 MILES. AXIAL REVOLUTION, 10H.
14M. PERIODIC TIME, 29T YEARS. MOONS, EIGHT.
The human mind has used Saturn and the two known planets beyond
for the last 200 years as a gymnasium. It has exercised itself
in comprehending their enormous distances in order to clear those
greater spaces, to where the stars are set; it has exercised its
ingenuity at interpreting appearances which signify something other
than they seem, in order that it may no longer be deluded by any
sunrises into a belief that the heavenly dome goes round the earth.
That a wandering point of light should develop into such amazing
grandeurs under the telescope, is as unexpected as that every tiny
seed should show peculiar markings and colors under the microscope.
[Illustration: Fig. 65.--View of Saturn and his Rings.]
There are certain things that are easy to determine, such as size,
density, periodic time, velocity, etc.; but other things are exceedingly
difficult to determine. It requires long sight to read when the
book is held [Page 168] 800,000,000 miles away. Only very few, if
more than two, opportunities have been found to determine the time
of Saturn's rotation. On the evening of December 7th, 1870,
Professor Hall observed a brilliant white spot suddenly show itself
on the body of this planet. It was as if an eruption of white hot
matter burst up from the interior. It spread eastward, and remained
bright till January, when it faded. No such opportunity for getting
a basis on which to found a calculation of the time of the rotation
of Saturn has occurred since Sir William Herschel's observations;
and, very singularly, the two times deduced wonderfully
coincide--that of Herschel being 10h. 16m., that of Mr. Hall being
10h. 14m.
[Page 169]
The density of Saturn is less than that of water, and its velocity
of rotation so great that centrifugal force antagonizes gravitation
to such an extent that bodies weigh on it about the same as on the
earth. All the fine fancies of the habitability of this vaporous
world, all the calculations of the number of people that could
live on the square miles of the planet and its enormous rings,
are only fancy. Nothing could live there with more brains than a
fish, at most. It is a world in formative processes. We cannot hear
the voice of the Creator there, but we can see matter responsive
to the voice, and moulded by his word.
_Rings of Saturn._
The eye and mind of man have worked out a problem of marvellous
difficulty in finding a true solution of the strange appearance
of the rings. Galileo has the immortal honor of first having seen
something peculiar about this planet. He wrote to the Duke of Tuscany,
"When I view Saturn it seems _tricorps_. The central body seems the
largest. The two others, situated, the one on the east, and the
other on the west, seem to touch it. They are like two supporters,
who help old Saturn on his way, and always remain at his side."
Looking a few years later, the rings having turned from view, he
said, "It is possible that some demon mocked me;" and he refused
to look any more.
Huyghens, in March, 1655, solved the problem of the triform appearance
of Saturn. He saw them as handles on the two sides. In a year they
had disappeared, and the planet was as round as it seemed to Galileo
in 1612. He did not, however, despair; and in October, [Page 170]
1656, he was rewarded by seeing them appear again. He wrote of
Saturn, "It is girdled by a thin plain ring, nowhere touching,
inclined to the ecliptic."
Since that time discoveries have succeeded one another rapidly.
"We have seen by degrees a ring evolved out of a triform planet,
and the great division of the ring and the irregularities on it
brought to light. Enceladus, and coy Mimas, faintest of twinklers,
are caught by Herschel's giant mirrors. And he, too, first of men,
realizes the wonderful tenuity of the ring, along which he saw
those satellites travelling like pearls strung on a silver thread.
Then Bond comes on the field, and furnishes evidence to show that
we must multiply the number of separate rings we know not how many
fold. And here we reach the golden age of Saturnian discovery,
when Bond, with the giant refractor of Cambridge, and Dawes, with
his 6-1/3-inch Munich glass, first beheld that wonderful dark
semi-transparent ring, which still remains one of the wonders of
our system. But the end is not yet: on the southern surface of
the ring, ere summer fades into autumn, Otto Struve in turn comes
upon the field, detects, as Dawes had previously done, a division
even in the dark ring, and measures it, while it is invisible to
Lassell's mirror--a proof, if one were needed, of the enormous
superiority possessed by refractors in such inquiries. Then we
approach 1861, when the ring plane again passes through the earth,
and Struve and Wray observe curious nebulous appearances."[*]
[Footnote *: Lockyer.]
Our opportunities for seeing Saturn vary greatly. As the earth at
one part of its orbit presents its south pole [Page 171] to the sun,
then its equator, then the north pole, so Saturn; and we, in the
direction of the sun, see the south side of the rings inclined at an
angle of 27°; next the edge of the rings, like a fine thread of
light; then the north side at a similar inclination. On February
7th, 1878, Saturn was between Aquarius and Pisces, with the edge of
the ring to the sun. In 1885, the planet being in Taurus, the south
side of the rings will be seen at the greatest advantage. From 1881
till 1885 all circumstances will combine to give most favorable
studies of Saturn. Meanwhile study the picture of it. The outer ring
is narrow, dark, showing hints of another division, sometimes more
evident than at others, as if it were in a state of flux. The inner,
or second, ring is much brighter, especially on the outer edge, and
shading off to the dusky edge next to the planet. There is no sign
of division into a third dusky innermost ring, as was plainly seen
by Bond. This, too, may be in a state of flux.
The markings of the planet are delicate, difficult of detection,
and are not like those stark zebra stripes that are so often
represented.
The distance between the planet and the second ring seems to be
diminished one-half since 1657, and this ring has doubled its breadth
in the same time. Some of this difference may be owing to our greater
telescopic power, enabling us to see the ring closer to the planet;
but in all probability the ring is closing in upon the central
body, and will touch it by A.D. 2150. Thus the whole ring must
ultimately fall upon the planet, instead of making a satellite.
We are anxious to learn the nature of such a ring. [Page 172]
Laplace mathematically demonstrated that it cannot be uniform and
solid, and survive. Professor Peirce showed it could not be fluid,
and continue. Then Professor Maxwell showed that it must be formed
of clouds of satellites too small to be seen individually, and too
near together for the spaces to be discerned, unless, perhaps, we
may except the inner dark ring, where they are not near enough to
make it positively luminous. Indeed, there is some evidence that the
meteoroids are far enough apart to make the ring partially
transparent.
We look forward to the opportunities for observation in 1882 with
the brightest hope that these difficult questions will be solved.
_Satellites of Saturn._
The first discovered satellite of Saturn seen by Huyghens was in
1655, and the last by the Bonds, father and son, of Cambridge,
in 1848. These are eight in number, and are named:
Distant from Saturn's centre.
I. Mimas 119,725 miles.
II. Enceladus 153,630 "
III. Tethys 190,225 "
IV. Dione 243,670 "
V. Rhea 340,320 "
VI. Titan 788,915 "
VII. Hyperion 954,160 "
VIII. Japetus 2,292,790 "
Titan can be seen by almost any telescope; I., II., and III., only
by the most powerful instrument. All except Japetus revolve nearly
in the plane of the ring. Like the moons of Jupiter, they present
remarkable and unaccountable variations of brilliancy. An inspection
[Page 173] of the table reveals either an expectation that another
moon will be discovered between V. and VI., and about three more
between VII. and VIII., or that these gaps may be filled with groups
of invisible asteroids, as the gap between Mars and Jupiter. This
will become more evident by drawing Saturn, the rings, and orbits of
the moons all as circles, on a scale of 10,000 miles to the inch.
Saturn will be in the centre, 70,000 miles in diameter; then a gap,
decreasing twenty-nine miles a year to the first ring, of, say,
10,000 miles; a dark ring 9000 miles wide; next the brightest ring
18,300 miles wide; then a gap of 1750 miles; then the outer ring
10,000 miles wide; then the orbits of the satellites in order.
If the scenery of Jupiter is magnificent, that of Saturn must be
sublime. If one could exist there, he might wander from the illuminated
side of the rings, under their magnificent arches, to the darkened
side, see the swift whirling moons; one of them presenting ten times
the disk of the earth's moon, and so very near as to enable him
to watch the advancing line of light that marks the lunar morning
journeying round that orb.