On a clear night you can often see, stretching across the sky, a track
of faint light, which is known to astronomers as the “Milky Way.” It
extends below the horizon and then round the earth to form a girdle
about the heavens. When we examine the Milky Way with a telescope we
find, to our amazement, that it consists of myriads of stars, so small
and so faint that we are not able to distinguish them individually; we
merely see the glow produced from their collective rays. Remembering
that our sun is a star, and that the Milky Way surrounds us, it would
almost seem as if our sun were but one of the host of stars which form
this cluster.
[Illustration: FIG. 83.--Globular Cluster in the Centaur.]
There are also other clusters of stars, some of which are exquisitely
beautiful telescopic spectacles. I may mention a celebrated pair of
these objects which lies in the constellation of Perseus. The sight of
them in a great telescope is so imposing that no one who is fit to
look through a telescope could resist a shout of wonder and admiration
when first they burst on his view. But there are other clusters. Here
is a picture of one which is known as the “Globular Cluster in the
Centaur” (Fig. 83). It consists of a ball of stars, so far off that,
however large these several suns may actually be, they have dwindled
down to extremely small points of light. A homely illustration may
serve to show the appearance which a globular cluster presents in a
good telescope. I take a pepper-castor and on a sheet of white paper
I begin to shake out the pepper until there is a little heap at the
centre and other grains are scattered loosely about. Imagine that
every one of those grains of pepper was to be transformed into a tiny
electric light, and then you have some idea of what a cluster of stars
would look like when viewed through a telescope of sufficient power.
There are multitudes of such groups scattered through the depths of
space. They require our biggest telescopes to show them adequately.
We have seen that our sun is a star, being only one of a magnificent
cluster that form the Milky Way. We have also seen that there are other
groups scattered through the length and depth of space. It is thus we
obtain a notion of the rank which our earth holds in the scheme of
things celestial.