Astronomy with an Opera-glass: A Popular Introduction to the Study of the Starry Heavens with the Simplest of Optical InstrumentsServiss, Garrett Putman
Science
Astronomy with an Opera-glass: A Popular Introduction to the Study of the Starry Heavens with the Simplest of Optical Instruments
Serviss, Garrett Putman
Astronomy
You will find it very interesting to take your glass and, beginning with
the attractive little group in the Northern Fish, follow the windings of
the ribbon, with its wealth of tiny stars, to the Western Fish. When you
have arrived at that point, sweep well over the sky in that
neighborhood, and particularly around and under the stars Iota ([iota]),
Theta ([theta]), Lambda ([lambda]), and Kappa ([kappa]). If you are
using a powerful glass, you will be surprised and delighted by what you
see. Below the star Omega ([omega]), and to the left of Lambda, is the
place which the sun occupies at the time of the spring equinox--in other
words, one of the two crossing-places of the equinoctial or the equator
of the heavens, and the ecliptic, or the sun's path. The prime meridian
of the heavens passes through this point. You can trace out this great
circle, from which astronomical longitudes are reckoned, by drawing an
imaginary line from the equinoctial point just indicated through [alpha]
in Andromeda and [beta] in Cassiopeia to the pole-star.
To the left of Pisces, and above the head of Cetus, is the constellation
Aries, or the Ram. Two pretty bright stars, four degrees apart, one of
which has a fainter star near it, mark it out plainly to the eye. These
stars are in the head of the Ram. The brightest one, Alpha ([alpha]), is
called Hamal; Beta ([beta]) is named Sheratan; and its fainter neighbor
is Mesarthim. According to fable, this constellation represents the ram
that wore the golden fleece, which was the object of the celebrated
expedition of the Argonauts. There is not much in the constellation to
interest us, except its historical importance, as it was more than two
thousand years ago the leading constellation of the zodiac, and still
stands first in the list of the zodiacal signs. Owing to the precession
of the equinoxes, however, the vernal equinoctial point, which was
formerly in this constellation, has now advanced into the constellation
Pisces, as we saw above. Gamma ([gamma]), Arietis, is interesting as the
first telescopic double star ever discovered. Its duplicity was detected
by Dr. Hooke while watching the passage of a comet near the star in
1664. Singularly enough, the brightest star in the constellation, now
bearing the letter [alpha], originally did not belong to the
constellation. Tycho Brahe finally placed it in the head of Aries.
The little constellation of the Triangles, just above Aries, is worth
only a passing notice. Insignificant as it appears, this little group is
a very ancient constellation. It received its name, Deltoton, from the
Greek letter [Delta].
[Illustration: MAP 17.]
Public-domain text, read in full here on John Shaqi.
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