ong. 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.

As regards the tilt of their orbits, some are actually as much as
34 degrees inclined to the ecliptic, so that in fact they are
seen from the Earth among our polar constellations.

176

From all this you see that Mars occupies a rather hot comer in
the solar system. Is it not possible that more than once in the
remote past Mars may have encountered one of these wanderers? If
he came within a certain distance of the small body his great
mass would sway it from its orbit, and under certain conditions
he would pick up a satellite in this manner. That his present
satellites were actually so acquired is the suggestion of Newton,
of Yale College.

Mars' satellites are indeed suspiciously and most abnormally
small. I have not time to prove this to you by comparison with
the other worlds of the solar system. In fact, they were not
discovered till 1877--although they were predicted in a most
curious manner, with the most uncannily accurate details, by
Swift.

One of these bodies is about 36 miles in diameter. This is
Phobos. Phobos is only 3.700 miles from the surface of Mars. The
other is smaller and further off. He is named Deimos, and his
diameter is only 10 miles. He is 12,500 miles from Mars' surface.
With the exception of Phobos the next smallest satelli