been positively proved
that they cannot be made of continuous matter, either liquid or solid,
for the force of gravity acting on them from the planet would tear them
to pieces. What, then, can they be? It is now pretty generally believed
that they are composed of multitudes of tiny bodies, each separate, and
circling separately round the great planet, as the asteroids circle
round the sun. As each one is detached from its neighbour and obeys its
own impulses, there is none of the strain and wrench there would be were
they all connected. According to the laws which govern planetary bodies,
those which are nearest to the planet will travel more quickly than
those which are further away. Of course, as we look at them from so
great a distance, and as they are moving, they appear to us to be
continuous. It is conjectured that the comparative darkness of the
inside ring is caused by the fact that there are fewer of the bodies
there to reflect the sunlight. Then, in addition to the rings, enough
themselves to distinguish him from all other planets, there are the ten
moons of richly-endowed Saturn to be considered. It is difficult to
gather much about these moons, on account of our great distance from
them. The largest is probably twice the diameter of our own moon. One of
them seems to be much brighter--that is to say, of higher reflecting
power--on one side than the other, and by distinguishing the sides
and watching carefully, astronomers have come to the conclusion that it
presents always the same face to Saturn in the same way as our own moon
does to us; in fact, there is reason to think that all the moons of
large planets do this.

[Illustration: THE PLANET SATURN WITH TWO OF HIS MOONS.]

All the moons lie outside the rings, and some at a very great distance
from Saturn, so that they can only appear small as seen from him. Yet at
the worst they must be brighter than ordinary stars, and add greatly to
the variations in the sky scenery of this beautiful planet. In
connection with Saturn's moons there is another of those astonishing
facts that are continually cropping up to remind us that, however much
we know, there is such a vast deal of which we are still ignorant. So
far in dealing with all the planets and moons in the solar system we
have made no remark on the way they rotate or revolve, because they all
go in the same direction, and that direction is called
counter-clockwise, which means that if you stand facing a cl