Possibly these masses were
prevented from falling back into the sun by the attraction of the
colliding body, or the body which caused the eruption. They would
revolve round the parent body, and the shoals of smaller
particles would gather about them by gravitation. If there were
any large region in the arm of the nebula which had no single
massive nucleus, the cosmic dust would gather about a number of
smaller centres. Thus might be explained the hundreds of
planetoids, or minor planets, which we find between Mars and
Jupiter. If these smaller bodies came within the sphere of
influence of one of the larger planets, yet were travelling
quickly enough to resist its attraction, they would be compelled
to revolve round it, and we could thus explain the ten satellites
of Saturn and the eight of Jupiter. Our moon, we shall see, had a
different origin.
We shall find this new hypothesis crossing the familiar lines at
many points in the next few chapters. We will consider those
further consequences as they arise, but may say at once that,
while the new theory has greatly helped us in tracing the
formation of the planetary system, astronomers are strongly
opposed to its claim that the planets did not pass through an
incandescent stage.
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