less in a solid state to bury itself deep
in the soil, the majority of these celestial visitants constitute no
source of danger whatever for us. Any one who will take the trouble to
gaze at the sky for a short time on a clear night, is fairly certain to
be rewarded with the view of a meteor. The impression received is as if
one of the stars had suddenly left its accustomed place, and dashed
across the heavens, leaving in its course a trail of light. It is for
this reason that meteors are popularly known under the name of "shooting
stars."

[1] By the Italian astronomer, Piazzi, at Palermo.

[2] Probably eight. (See note, page 232.)

CHAPTER III

THE SOLAR SYSTEM

We have seen, in the course of the last chapter, that the solar system
is composed as follows:--there is a central body, the sun, around which
revolve along stated paths a number of important bodies known as
planets. Certain of these planets, in their courses, carry along in
company still smaller bodies called satellites, which revolve around
them. With regard, however, to the remaining members of the system, viz.
the comets and the meteors, it is not advisable at this stage to add
more to what has been said in the preceding chapter. For the time being,
therefore, we will devote our attention merely to the sun, the planets,
and the satellites.

Of what shape then are these bodies? Of one shape, and that one alone
which appears to characterise all solid objects in the celestial spaces:
they are spherical, which means _round like a ball_.

Each of these spherical bodies rotates; that is to say, turns round and
round, as a top does when it is spinning. This rotation is said to take
place "upon an axis," a statement which may be explained as
follows:--Imagine a ball with a knitting-needle run right through its
centre. Then imagine this needle held pointing in one fixed direction
while the ball is turned round and round. Well, it is the same thing
with the earth. As it journeys about the sun, it keeps turning round and
round continually as if pivoted upon a mighty knitting needle
transfixing it from North Pole to South Pole. In reality, however, there
is no such material axis to regulate the constant direction of the
rotation, just as there are no actual supports to uphold the earth
itself in space. The causes which keep the celestial spheres poised, and
which control their motions, are far more wonderful than any mechanical
device.

At this jun