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of miles into the region of the heavens which lies outside Mars'
orbit.
Between Mars and Jupiter is a chasm of 341 millions of miles.
This gap in the sequence of planets was long known to be quite
out of keeping with the orderly succession of worlds outward from
the Sun. A society was formed at the close of the last century
for the detection of the missing world. On the first day of the
last century, Piazzi—who, by the way, was not a member of the
society—discovered a tiny world in the vacant gap. Although
eagerly welcomed, as better than nothing, it was a disappointing
find. The new world was a mere rock. A speck of about 160 miles
in diameter. It was obviously never intended that such a body
should have all this space to itself. And, sure enough, shortly
after, another small world was discovered. Then another was
found, and another, and so on; and now more than 400 of these
strange little worlds are known.
But whence came such bodies? The generally accepted belief is
that these really represent a misbegotten world. When the Sun was
younger he shed off the several worlds of our system as so many
rings. Each ring then coalesced into a world. Neptune being the
first born; Mercury the youngest born.
After Jupiter was thrown off, and the Sun had shrunk away inwards
some 20o million miles, he shed off another ring. Meaning that
this offspring of his should grow up like the rest, develop into
a stable world with the
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potentiality even, it may be, of becoming the abode of rational
beings. But something went wrong. It broke up into a ring of
little bodies, circulating around him.
It is probable on this hypothesis that the number we are
acquainted with does not nearly represent the actual number of
past and present asteroids. It would take 125,000 of the biggest
of them to make up a globe as big as our world. They, so far as
they are known, vary in size from 10 miles to 160 miles in
diameter. It is probable then—on the assumption that this failure
of a world was intended to be about the mass of our Earth—that
they numbered, and possibly number, many hundreds of thousands.
Some of these little bodies are very peculiar in respect to the
orbits they move in. This peculiarity is sometimes in the
eccentricity of their orbits, sometimes in the manner in which
their orbits are tilted to the general plane of the ecliptic, in
which all the other planets move.
The eccentricity, according to Proctor, in some cases may attain
such extremes as to bring the little world inside Mars' mean
distance from the sun. This, as you will remember, is very much
less than his greatest distance from the sun. The entire belt of
asteroids—as known—lie much nearer to Mars than to Jupiter.