The story of the universe. Volume 1 (of 4) : $b The starry skies
History
The story of the universe. Volume 1 (of 4) : $b The starry skies
Astronomy; Earth (Planet); Natural history
There are other interesting specimens of the globular class in the
Southern Hemisphere, but not of such large apparent dimensions as
those already described. Of these may be mentioned 22 Messier, which
lies about midway between the stars Mu and Sigma Sagittarii. It is
described by Sir John Herschel as a fine globular cluster, with stars
of two magnitudes, namely eleven or twelve, and fifteen or sixteen,
the larger being visibly reddish, and he suggested that it consists
of “two layers, or one shell over another.” Owing to the comparative
brightness of the larger components, this cluster forms a good object
for small telescopes. I saw the brighter stars well with a 3-inch
refractor in the Punjab sky, but, of course, the greater portion of
the cluster has a nebulous appearance in a telescope of this size.
Between Alpha and Beta Scorpii there is a condensed globular cluster.
With small telescopes it very much resembles a telescopic comet, but
with larger instruments its true character is revealed. Sir William
Herschel considered it “the richest and most condensed mass of stars
in the firmament.” In May, 1860, a “temporary star” of the seventh
magnitude suddenly appeared in the centre, almost blotting out the
cluster by its superior light. The star faded away before the end
of June of the same year, and has not been seen with any certainty
since. It has been suggested that this temporary star lay _between_
the cluster and the earth, but it seems to me much more probable that
the outburst took place _in_ the cluster itself, and that it was
possibly caused by a collision between two of the component stars,
or by a swarm of meteors rushing with a high velocity through the
cluster.
The beauty and sublimity of the spectacle presented by these globular
clusters, when viewed with a powerful telescope, is such as can not
be adequately described, and it has been said that when seen for the
first time, “few can refrain from a shout of rapture.” The component
stars, although distinctly visible as points of light, defy all
attempts at counting them, and seem literally innumerable. Placed
like a mass of glittering diamond-dust on the dark background of
the heavens, they impress us forcibly with the idea that if each of
these lucid points is a sun, the thousands which seem massed together
in so small a space must be in reality either relatively close and
individually small, or else the system of suns must be placed at a
distance almost approaching the infinite.
Public-domain text, read in full here on John Shaqi.
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