wth of our
telescopes and the application of photography we wonder whether we may
as yet see only a fraction of the real universe, as small in comparison
with the whole as the Babylonian system was in comparison with ours. We
must be content to wonder. Some affirm that the universe is infinite;
others that it is limited. We have no firm ground in science for either
assertion. Those who claim that the system is limited point out that, as
the stars decrease in brightness, they increase so enormously in number
that the greater faintness is more than compensated, and therefore, if
there were an infinite series of magnitudes, the midnight sky would be a
blaze of light. But this theoretical reasoning does not allow for dense
regions of space that may obstruct the light, or vast regions of vacancy
between vast systems of stars. Even apart from the evidence that dark
nebulae or other special light-absorbing regions do exist, the question
is under discussion in science at the present moment whether light is
not absorbed in the passage through ordinary space. There is reason to
think that it is. Let us leave precarious speculations about finiteness
and infinity to philosophers, and take the universe as we know it.

Picture, then, on the more moderate estimate, these 500,000,000 suns
scattered over tens of thousands of billions of miles. Whether they form
one stupendous system, and what its structure may be, is too obscure a
subject to be discussed here. Imagine yourself standing at a point
from which you can survey the whole system and see into the depths and
details of it. At one point is a single star (like our sun), billions
of miles from its nearest neighbour, wearing out its solitary life in a
portentous discharge of energy. Commonly the stars are in pairs, turning
round a common centre in periods that may occupy hundreds of days or
hundreds of years. Here and there they are gathered into clusters,
sometimes to the number of thousands in a cluster, travelling together
over the desert of space, or trailing in lines like luminous caravans.
All are rushing headlong at inconceivable speeds. Few are known to be so
sluggish as to run, like our sun, at only 8000 miles an hour. One of
the "fixed" stars of the ancients, the mighty Arcturus, darts along at
a rate of more than 250 miles a second. As they rush, their surfaces
glowing at a temperature anywhere between 1000 and 20,000 degrees C.,
they shake the environing space with electr