"Broad and ample road whose dust is gold,
And pavement stars, as stars to thee appear
Seen in the galaxy, that milky way
Which nightly as a circling zone thou seest
Powder'd with stars."
--MILTON, _Paradise Lost_.
On clear, winter evenings one may see a portion of the zone of
the Milky Way, which encircles the heavens, arching magnificently
across the heavens as it passes from Cassiopeia and Cepheus in the
northwest, through Perseus and Auriga and the eastern part of Taurus,
across the feet of Gemini, between Canis Minor and Orion and through
the eastern part of Canis Major to the southern horizon.
At this point it passes beyond our range of vision into the
star-groups of Puppis, Vela and Carina, subdivisions of the huge
southern constellation of Argo Navis. It reaches its greatest
distance south of the celestial equator and also attains its greatest
brilliancy in Crux, the far-famed Southern Cross. From here it turns
northward once more, passing into Centaurus, Musca, Circinus Ara and
Lupus constellations of the southern hemisphere and comes within our
range of vision again in Sagittarius and Scorpio. Here the Milky Way
divides into two branches, though some astronomers now believe that
this apparent division into two branches is due to the presence of an
enormous cloud of non-luminous matter lying along the course of the
Milky Way at this point, similar in its nature to the dark "holes"
and "caves" and streaks that appear in all portions of the Milky Way
and most noticeably athwart its course in Argo and Centaurus.
One of these branches of the Milky Way passes from Sagittarius
through Aquila to Cygnus and the other through Scorpio, Ophiuchus and
Serpens to Cygnus, the two extending diagonally across the heavens
in the late summer and early fall evenings from the northeast to
the southwest. From Cygnus, the Milky Way passes into Cepheus and
Cassiopeia and thus completes its circuit of the heavens.
It is not seen to advantage in spring or early summer evenings
because it then rests nearly on the horizon. Its plane is inclined
about 63° to the celestial equator and its poles lie in the
constellations of Coma Berenicis and Cetus. These are the two points
that lie farthest from the Milky Way.
The Milky Way has been called the groundwork of the universe. By far
the greater number of all the stars are crowded towards its plane in
the form of an enormous flattened disk or lens.
Our solar system, it has been estimated, lies close to the plane of
the Milky Way and at a distance of some 50,000 or 60,000 light-years
from its center. The diameter of the Milky Way as deduced from Dr.
Harlow Shapley's work on globular star clusters is about 300,000
light-years in extent, or ten times greater than the limit set some
years ago.
Public-domain text, read in full here on John Shaqi.
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