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
The redness of the light of Aldebaran is a very interesting phenomenon.
Careful observation detects a decided difference between its color and
that of Betelgeuse, or Alpha Orionis, which is also a red star. It
differs, too, from the brilliant red star of summer, Antares. Aldebaran
has a trace of rose-color in its light, while Betelgeuse is of a very
deep orange, and Antares may be described as fire-red. These shades of
color can easily be detected by the naked eye after a little practice.
First compare Aldebaran and Betelgeuse, and glance from each to the
brilliant white, or bluish-white, star Rigel in Orion's foot. Upon
turning the eye back from Rigel to Aldebaran the peculiar color of the
latter is readily perceived. Spectroscopic analysis has revealed the
presence in Aldebaran of hydrogen, sodium, magnesium, calcium, iron,
bismuth, tellurium, antimony, and mercury. And so modern discoveries,
while they have pushed back the stars to distances of which the ancients
could not conceive, have, at the same time, and equally, widened the
recognized boundaries of the physical universe and abolished forever the
ancient distinction between the heavens and the earth. It is a plain
road from the earth to the stars, though mortal feet can not tread it.
[Illustration: THE HYADES.]
Keeping in mind that in our little picture of the Hyades the top is
north, the right hand west, and the left hand east, the reader will be
able to identify the principal stars in the group. Aldebaran is readily
recognized, because it is the largest of all. The bright star near the
upper edge of the picture is Epsilon Tauri, and its sister star, forming
the point of the [V], is Gamma Tauri. The three brightest stars between
Epsilon and Gamma, forming a little group, are the Deltas, while the
pair of stars surrounded by many smaller ones, half-way between
Aldebaran and Gamma, are the Thetas. These stars present a very pretty
appearance, viewed with a good glass, the effect being heightened by a
contrast of color in the two Thetas. The little pair southeast of
Aldebaran, called the Sigmas, is also a beautiful object. The distance
apart of these stars is about seven minutes of arc, while the distance
between the two Thetas is about five and a half minutes of arc. These
measures may be useful to the reader in estimating the distances between
other stars that he may observe. It will also be found an interesting
test of the eye-sight to endeavor to see these stars as doubles without
the aid of a glass. Persons having keen eyes will be able to accomplish
this.
Public-domain text, read in full here on John Shaqi.
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