With the
powerful instruments which are now in use for photographing the
sky, the number of stars brought to light must rise into the
hundreds of millions, and the greater part of these belong to the
Milky Way. The smaller the stars we count, the greater their
comparative number in the region of the Milky Way. Of the stars
visible through the telescope, more than one-half are found in the
Milky Way, which may be regarded as a girdle spanning the entire
visible universe.
Of the diameter of this girdle we can say, almost with certainty,
that it must be more than a thousand times as great as the
distance of the nearest fixed star from us, and is probably two or
three times greater. According to the best judgment we can form,
our solar system is situate near the central region of the girdle,
so that the latter must be distant from us by half its diameter.
It follows that if we can imagine a gigantic pair of compasses, of
which the points extend from us to Alpha Centauri, the nearest
star, we should have to measure out at least five hundred spaces
with the compass, and perhaps even one thousand or more, to reach
the region of the Milky Way.
With this we have to connect another curious fact.
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