80. To Saturn, the Sun appears only 1/90th part so big as to us; and the
light and heat he receives from the Sun are in the same proportion to
ours. But to compensate for the small quantity of sun-light, he has five
Moons, all going round him on the outside of his Ring, and nearly in the
same plane with it. The first, or nearest Moon to Saturn, goes round him
in 1 day 21 hours 19 minutes; and is 140 thousand miles from his center:
The second, in two days 17 hours 40 minutes; at the distance of 187
thousand miles: The third, in 4 days 12 hours 25 minutes; at 263
thousand miles distance: The fourth, in 15 days 22 hours 41 minutes; at
the distance of 600 thousand miles: And the fifth, or outermost, at one
million 800 thousand miles from Saturn’s center, goes round him in 79
days 7 hours 48 minutes. Their Orbits in the Scheme of the Solar System
are represented by the five small circles, marked 1. 2. 3. 4. 5. on
Saturn’s Orbit; but these, like the Orbits of the other Satellites, are
drawn fifty times too large in proportion to the Orbits of their Primary
Planets.
[Sidenote: His Axis probably inclined to his Ring.]
81. The Sun shines almost fifteen of our years together on one side of
Saturn’s Ring without setting, and as long on the other in it’s turn. So
that the Ring is visible to the inhabitants of that Planet for almost
fifteen of our years, and as long invisible by turns, if it’s Axis has
no Inclination to it’s Ring: but if the Axis of the Planet be inclined
to the Ring, suppose about 30 degrees, the Ring will appear and
disappear once every natural day to all the inhabitants within 30
degrees of the Equator, on both sides, frequently eclipsing the Sun in a
Saturnian day. Moreover, if Saturn’s Axis be so inclined to his Ring, it
is perpendicular to his Orbit; and thereby the inconvenience of
different seasons to that Planet is avoided. For considering the length
of Saturn’s year, which is almost equal to thirty of ours, what a
dreadful condition must the inhabitants of his Polar regions be in, if
they be half of that time deprived of the light and heat of the Sun?
which must not be their case alone, if the Axis of the Planet be
perpendicular to the Ring, but also the Ring must hide the Sun from vast
tracks of land on each side of the Equator for 13 or 14 of our years
together, on the south side and north side by turns, as the Axis
inclines to or from the Sun: the reverse of which inconvenience is
another good presumptive proof of the Inclination of Saturn’s Axis to
it’s Ring, and also of his Axis being perpendicular to his Orbit.
[Sidenote: How the Ring appears to Saturn and to us.
In what Signs Saturn appears to lose his Ring; and in what
Signs it appears most open to us.]
82. This Ring, seen from Saturn, appears like a vast luminous Arch in
the Heavens, as if it did not belong to the Planet. When we see the Ring
most open, it’s shadow upon the Planet is broadest; and from that time
the shadow grows narrower, as the Ring appears to do to us; until, by
Saturn’s annual motion, the Sun comes to the plane of the Ring, or even
with it’s edge; which being then directed towards us, becomes invisible
on account of it’s thinness; as shall be explained more largely in the
tenth Chapter, and illustrated by a figure. The Ring disappears twice in
every annual Revolution of Saturn, namely, when he is in the 19th degree
both of Pisces and of Virgo. And when Saturn is in the middle between
these points, or in the 19th degree either of Gemini or of Sagittarius,
his Ring appears most open to us; and then it’s longest diameter is to
it’s shortest as 9 to 4.
[Sidenote: No Planet but Saturn can be seen from Jupiter; nor any from
Jupiter besides Saturn.]
83. To such eyes as ours, unassisted by instruments, Jupiter is the only
Planet that can be seen from Saturn; and Saturn the only Planet that can
be seen from Jupiter. So that the inhabitants of these two Planets must
either see much farther than we do, or have equally good instruments to
carry their sight to remote objects, if they know that there is such a
body as our Earth in the Universe: for the Earth is no bigger seen from
Jupiter than his Moons are seen from the Earth; and if his large body
had not first attracted our sight, and prompted our curiosity to view
him with the telescope, we should never have known any thing of his
Moons; unless by chance we had directed the telescope toward that small
part of the Heavens where they were at the time of observation. And the
like is true of the Moons of Saturn.
[Sidenote: Place of Saturn’s Nodes.]
84. The Orbit of Saturn is 2-1/2 degrees inclined to the Ecliptic, or
Orbit of our Earth, and intersects it in the 21st degree of Cancer and
of Capricorn; so that Saturn’s Nodes are only 14 degrees from Jupiter’s,
§ 77.
[Sidenote: The Sun’s light much stronger on Jupiter and Saturn than is
generally believed.