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ASTRONOMY
WITH AN OPERA-GLASS
A POPULAR INTRODUCTION TO THE STUDY OF THE STARRY
HEAVENS WITH THE SIMPLEST OF OPTICAL INSTRUMENTS
WITH MAPS AND DIRECTIONS TO FACILITATE THE RECOGNITION
OF THE CONSTELLATIONS AND THE PRINCIPAL STARS VISIBLE
TO THE NAKED EYE
BY
GARRETT P. SERVISS
"Known are their laws; in harmony unroll
The nineteen-orbed cycles of the Moon.
And all the signs through which Night whirls her car
From belted Orion back to Orion and his dauntless Hound,
And all Poseidon's, all high Zeus' stars
Bear on their beams true messages to man."
POSTE'S ARATUS.
_THIRD EDITION_
NEW YORK
D. APPLETON AND COMPANY
LONDON: CAXTON HOUSE, PATERNOSTER SQUARE
1890
COPYRIGHT, 1888,
BY D APPLETON AND COMPANY.
TO THE READER
In the pages that follow, the author has endeavored to encourage the
study of the heavenly bodies by pointing out some of the interesting and
marvelous phenomena of the universe that are visible with little or no
assistance from optical instruments, and indicating means of becoming
acquainted with the constellations and the planets. Knowing that an
opera-glass is capable of revealing some of the most beautiful sights in
the starry dome, and believing that many persons would be glad to learn
the fact, he set to work with such an instrument and surveyed all the
constellations visible in the latitude of New York, carefully noting
everything that it seemed might interest amateur star-gazers. All the
objects thus observed have not been included in this book, lest the
multiplicity of details should deter or discourage the very readers for
whom it was specially written. On the other hand, there is nothing
described as visible with an opera-glass or a field-glass which the
author has not seen with an instrument of that description, and which
any person possessing eye-sight of average quality and a competent glass
should not be able to discern.
But, in order to lend due interest to the subject, and place it before
the reader in a proper light and true perspective, many facts have been
stated concerning the objects described, the ascertainment of which has
required the aid of powerful telescopes, and to observers with such
instruments is reserved the noble pleasure of confirming with their own
eyes those wonderful discoveries which the looker with an opera-glass
can not hope to behold unless, happily, he should be spurred on to the
possession of a telescope. Yet even to glimpse dimly these distant
wonders, knowing what a closer view would reveal, is a source of no mean
satisfaction, while the celestial phenomena that lie easily within reach
of an opera-glass are sufficient to furnish delight and instruction for
many an evening.
It should be said that the division of the stars used in this book into
the "Stars of Spring," "Stars of Summer," "Stars of Autumn," and "Stars
of Winter," is purely arbitrary, and intended only to indicate the
seasons when certain constellations are best situated for observation or
most conspicuous.
The greater part of the matter composing this volume appeared originally
in a series of articles contributed by the author to "The Popular
Science Monthly" in 1887-'88. The reception that those articles met with
encouraged him to revise and enlarge them for publication in the more
permanent form of a book.
G. P. S.
BROOKLYN, N. Y., _September, 1888._
CONTENTS.
PAGE
INTRODUCTION 1
Popular interest in the phenomena of the heavens.
The opera-glass as an instrument of observation for beginners
in star-study.
Testing an opera-glass.
CHAPTER I.
THE STARS OF SPRING 7
_Description of the Constellations_--Auriga, the Charioteer;
Berenice's Hair; Cancer, the Crab [the Manger]; Canis
Minor, the Lesser Dog; Corvus, the Crow; Crateris, the
Cup; Gemini, the Twins; Hydra, the Water-Serpent; Leo,
the Lion; Ursa Major, the Greater Bear [the Great Dipper];
Ursa Minor, the Lesser Bear [the Pole-Star].
A circular index-map, maps on a larger scale, of the
constellations described, and pictures of remarkable
objects.
CHAPTER II.
THE STARS OF SUMMER 30
_Description of the Constellations_--Aquila, the Eagle;
Booetes, the Herdsman, or Bear-Diver; Canes Venatici,
the Hunting-Dogs; Cygnus, the Swan [the Northern Cross];
Delphinus, the Dolphin; Draco, the Dragon; Hercules
[the Great Sun-Swarm, 13 M]; Libra, the Balance; Lyra,
the Harp; the Northern Crown; Ophiuchus et Serpens,
the Serpent-bearer and the Serpent; Sagitta, the Arrow;
Sagittarius, the Archer; Scorpio, the Scorpion;
Sobieski's Shield; Taurus Poniatowskii, Poniatowsky's
Bull; Virgo, the Virgin [the Field of the Nebulae];
Vulpecula, the Little Fox.
A circular index-map, maps, on a larger scale, of the
constellations described, and pictures of remarkable
objects.
CHAPTER III.
THE STARS OF AUTUMN 60
_Description of the Constellations_--Andromeda [the Great
Nebula]; Aquarius, the Water-Bearer; Aries, the Ram;
Capricornus, the Goat; Cassiopeia; Cepheus; Cetus,
the Whale [Mira, the wonderful variable star];
Pegasus, the Winged Horse.
Perseus [Algol, the Demon-Star]; Pisces, the Fishes;
Piscis Australis, the Southern Fish; the Triangles.
A circular index-map, maps on a larger scale, of the
constellations described, and pictures of remarkable
objects.
CHAPTER IV.
THE STARS OF WINTER 89
_Description of the Constellations_--Argo, Jason's Ship;
Canis Major, the Great Dog [Sirius]; Eridanus, the
river Po; Lepus, the Hare; Monoceros, the Unicorn;
Orion [the Great Nebula]; Taurus, the Bull [the
Pleiades and Hyades].
A circular index-map, maps on a larger scale, of the
constellations described, and pictures of remarkable
objects.
CHAPTER V.
THE MOON, THE PLANETS, AND THE SUN 118
Description of lunar "seas," mountains, and "craters,"
with a map of the moon, and cuts showing its appearance
with a field-glass.
_Opera-glass observation of_--The sun (one cut), Mercury,
Venus, Mars, Jupiter and his satellites (one cut),
Saturn, Uranus (three cuts).
ASTRONOMY WITH AN OPERA-GLASS.
INTRODUCTION.
Star-gazing was never more popular than it is now. In every civilized
country many excellent telescopes are owned and used, often to very good
purpose, by persons who are not practical astronomers, but who wish to
see for themselves the marvels of the sky, and who occasionally stumble
upon something that is new even to professional star-gazers. Yet,
notwithstanding this activity in the cultivation of astronomical
studies, it is probably safe to assert that hardly one person in a
hundred knows the chief stars by name, or can even recognize the
principal constellations, much less distinguish the planets from the
fixed stars. And of course they know nothing of the intellectual
pleasure that accompanies a knowledge of the stars. Modern astronomy is
so rapidly and wonderfully linking the earth and the sun together, with
all the orbs of space, in the bonds of close physical relationship, that
a person of education and general intelligence can offer no valid excuse
for not knowing where to look for Sirius or Aldebaran, or the Orion
nebula, or the planet Jupiter. As Australia and New Zealand and the
islands of the sea are made a part of the civilized world through the
expanding influence of commerce and cultivation, so the suns and planets
around us are, in a certain sense, falling under the dominion of the
restless and resistless mind of man. We have come to possess vested
intellectual interests in Mars and Saturn, and in the sun and all his
multitude of fellows, which nobody can afford to ignore.
A singular proof of popular ignorance of the starry heavens, as well as
of popular curiosity concerning any uncommon celestial phenomenon, is
furnished by the curious notions prevailing about the planet Venus. When
Venus began to attract general attention in the western sky in the early
evenings of the spring of 1887, speculation quickly became rife about
it, particularly on the great Brooklyn Bridge. As the planet hung
dazzlingly bright over the New Jersey horizon, some people appeared to
think it was the light of Liberty's torch, mistaking the bronze
goddess's real flambeau for a part of the electric-light system of the
metropolis. Finally (to judge from the letters written to the
newspapers, and the questions asked of individuals supposed to know
something about the secrets of the sky), the conviction seems to have
become pretty widely distributed that the strange light in the west was
no less than an electrically illuminated balloon, nightly sent skyward
by Mr. Edison, for no other conceivable reason than a wizardly desire to
mystify his fellow-men. I have positive information that this ridiculous
notion has been actually entertained by more than one person of
intelligence. And as Venus glowed with increasing splendor in the serene
evenings of June, she continued to be mistaken for some petty artificial
light instead of the magnificent world that she was, sparkling out there
in the sunshine like a globe of burnished silver. Yet Venus as an
evening star is not so rare a phenomenon that people of intelligence
should be surprised at it. Once in every 584 days she reappears at the
same place in the sunset sky--
"Gem of the crimson-colored even,
Companion of retiring day."
No eye can fail to note her, and as the nearest and most beautiful of
the Earth's sisters it would seem that everybody should be as familiar
with her appearance as with the face of a friend. But the popular
ignorance of Venus, and the other members of the planetary family to
which our mother, the Earth, belongs, is only an index of the denser
ignorance concerning the stars--the brothers of our great father, the
Sun. I believe this ignorance is largely due to mere indifference,
which, in its turn, arises from a false and pedantic method of
presenting astronomy as a creature of mathematical formulae, and a humble
handmaiden of the art of navigation. I do not, of course, mean to cast
doubt upon the scientific value of technical work in astronomy. The
science could not exist without it. Those who have made the spectroscope
reveal the composition of the sun and stars, and who are now making
photography picture the heavens as they are, and even reveal phenomena
which lie beyond the range of human vision, are the men who have taken
astronomy out of its swaddling-clothes, and set it on its feet as a
progressive science. But when one sees the depressing and repellent
effect that has evidently been produced upon the popular mind by the
ordinary methods of presenting astronomy, one can not resist the
temptation to utter a vigorous protest, and to declare that this
glorious science is not the grinning mathematical skeleton that it has
been represented to be.
Perhaps one reason why the average educated man or woman knows so little
of the starry heavens is because it is popularly supposed that only the
most powerful telescopes and costly instruments of the observatory are
capable of dealing with them. No greater mistake could be made. It does
not require an optical instrument of any kind, nor much labor, as
compared with that expended in the acquirement of some polished
accomplishments regarded as indispensable, to give one an acquaintance
with the stars and planets which will be not only pleasurable but
useful. And with the aid of an opera-glass most interesting, gratifying,
and, in some instances, scientifically valuable observations may be made
in the heavens. I have more than once heard persons who knew nothing
about the stars, and probably cared less, utter exclamations of surprise
and delight when persuaded to look at certain parts of the sky with a
good glass, and thereafter manifest an interest in astronomy of which
they would formerly have believed themselves incapable.
Being convinced that whoever will survey the heavens with a good
opera-glass will feel repaid many fold for his time and labor, I have
undertaken to point out some of the objects most worthy of attention,
and some of the means of making acquaintance with the stars.
First, a word about the instrument to be used. Galileo made his famous
discoveries with what was, in principle of construction, simply an
opera-glass. This form of telescope was afterward abandoned because very
high magnifying powers could not be employed with it, and the field of
view was restricted. But, on account of its brilliant illumination of
objects looked at, and its convenience of form, the opera-glass is still
a valuable and, in some respects, unrivaled instrument of observation.
In choosing an opera-glass, see first that the object-glasses are
achromatic, although this caution is hardly necessary, for all modern
opera-glasses, worthy of the name, are made with achromatic objectives.
But there are great differences in the quality of the work. If a glass
shows a colored fringe around a bright object, reject it. Let the
diameter of the object-glasses, which are the large lenses in the end
farthest from the eye, be not less than an inch and a half. The
magnifying power should be at least three or four diameters. A familiar
way of estimating the magnifying power is by looking at a brick wall
through one barrel of the opera-glass with one eye, while the other eye
sees the wall without the intervention of the glass. Then notice how
many bricks seen by the naked eye are required to equal in thickness one
brick seen through the glass. That number represents the magnifying
power.
The instrument used by the writer in making most of the observations for
this book has object-glasses 1.6 inch in diameter, and a magnifying
power of about 3.6 times.
See that the fields of view given by the two barrels of the opera-glass
coincide, or blend perfectly together. If one appears to partially
overlap the other when looking at a distant object, the effect is very
annoying. This fault arises from the barrels of the opera-glass being
placed too far apart, so that their optical centers do not coincide with
the centers of the observer's eyes.
[Illustration: A VERY BAD FIELD.]
Occasionally, on account of faulty centering of the lenses, a double
image is given of objects looked at, as illustrated in the accompanying
cut. In such a case the glass is worthless; but if the effect is simply
the addition of a small, crescent-shaped extension on one side of the
field of view without any reduplication, the fault may be overlooked,
though it is far better to select a glass that gives a perfectly round
field. Some glasses have an arrangement for adjusting the distance
between the barrels to suit the eyes of different persons, and it would
be well if all were made adjustable in the same way.
Don't buy a cheap glass, but don't waste your money on fancy mountings.
What the Rev. T. W. Webb says of telescopes is equally true of
opera-glasses: "Inferior articles may be showily got up, and the outside
must go for nothing." There are a few makers whose names, stamped upon
the instrument, may generally be regarded as a guarantee of excellence.
But the best test is that of actual performance. I have a field-glass
which I found in a pawn-shop, that has no maker's name upon it, but in
some respects is quite capable of bearing comparison with the work of
the best advertised opticians. And this leads me to say that, by the
exercise of good judgment, one may occasionally purchase superior
glasses at very reasonable prices in the pawn-shops. Ask to be shown the
old and well-tried articles; you may find among them a second-hand glass
of fine optical properties. If the lenses are not injured, one need not
trouble one's self about the worn appearance of the outside of the
instrument; so much the more evidence that somebody has found it well
worth using.
A good field or marine glass is in some respects better than an
opera-glass for celestial observations. It possesses a much higher
magnifying power, and this gives sometimes a decided advantage. But, on
the other hand, its field of view is smaller, rendering it more
difficult to find and hold objects. Besides, it does not present as
brilliant views of scattered star-clusters as an opera-glass does. For
the benefit of those who possess field-glasses, however, I have included
in this brief survey certain objects that lie just beyond the reach of
opera-glasses, but can be seen with the larger instruments.
I have thought it advisable in the descriptions of the constellations
which follow to give some account of their mythological origin, both
because of the historical interest which attaches to it, and because,
while astronomers have long since banished the constellation figures
from their maps, the names which the constellations continue to bear
require some explanation, and they possess a literary and romantic
interest which can not be altogether disregarded in a work that is not
intended for purely scientific readers.
CHAPTER I.
THE STARS OF SPRING.
Having selected your glass, the next thing is to find the stars. Of
course, one could sweep over the heavens at random on a starry night and
see many interesting things, but he would soon tire of such aimless
occupation. The observer must know what he is looking at in order to
derive any real pleasure or satisfaction from the sight.
It really makes no difference at what time of the year such observations
are begun, but for convenience I will suppose that they are begun in the
spring. We can then follow the revolution of the heavens through a year,
at the end of which the diligent observer will have acquired a competent
knowledge of the constellations. The circular map, No. 1, represents the
appearance of the heavens at midnight on the 1st of March, at eleven
o'clock on the 15th of March, at ten o'clock on the 1st of April, at
nine o'clock on the 15th of April, and at eight o'clock on the 1st of
May. The reason why a single map can thus be made to show the places of
the stars at different hours in different months will be plain upon a
little reflection. In consequence of the earth's annual journey around
the sun, the whole heavens make one apparent revolution in a year. This
revolution, it is clear, must be at the rate of 30 deg. in a month, since
the complete circuit comprises 360 deg.. But, in addition to the annual
revolution, there is a diurnal revolution of the heavens which is caused
by the earth's daily rotation upon its axis, and this revolution must,
for a similar reason, be performed at the rate of 15 deg. for each of the
twenty-four hours. It follows that in two hours of the daily revolution
the stars will change their places to the same extent as in one month of
the annual revolution. It follows also that, if one could watch the
heavens throughout the whole twenty-four hours, and not be interrupted
by daylight, he would behold the complete circuit of the stars just as
he would do if, for a year, he should look at the heavens at a
particular hour every night. Suppose that at nine o'clock on the 1st of
June we see the star Spica on the meridian; in consequence of the
rotation of the earth, two hours later, or at eleven o'clock, Spica will
be 30 deg. west of the meridian. But that is just the position which Spica
would occupy at nine o'clock on the 1st of July, for in one month
(supposing a month to be accurately the twelfth part of a year) the
stars shift their places 30 deg. toward the west. If, then, we should make a
map of the stars for nine o'clock on the 1st of July, it would answer
just as well for eleven o'clock on the 1st of June, or for seven o'clock
on the 1st of August.
[Illustration: MAP 1.]
The center of the map is the zenith, or point overhead. The reader must
now exercise his imagination a little, for it is impossible to represent
the true appearance of the concave of the heavens on flat paper. Holding
the map over your head, with the points marked East, West, North, and
South in their proper places, conceive of it as shaped like the inside
of an open umbrella, the edge all around extending clear down to the
horizon. Suppose you are facing the south, then you will see, up near
the zenith, the constellation of Leo, which can be readily recognized on
the map by six stars that mark out the figure of a sickle standing
upright on its handle. The large star in the bottom of the handle is
Regulus. Having fixed the appearance and situation of this constellation
in your mind, go out-of-doors, face the south, and try to find the
constellation in the sky. With a little application you will be sure to
succeed.
Using Leo as a basis of operations, your conquest of the sky will now
proceed more rapidly. By reference to the map you will be able to
recognize the twin stars of Gemini, southwest of the zenith and high up;
the brilliant lone star, Procyon, south of Gemini; the dazzling Sirius,
flashing low down in the southwest; Orion, with all his brilliants,
blazing in the west; red Aldebaran and the Pleiades off to his right;
and Capella, bright as a diamond, high up above Orion, toward the north.
In the southeast you will recognize the quadrilateral of Corvus, with
the remarkably white star Spica glittering east of it.
Next face the north. If you are not just sure where north is, try a
pocket-compass. This advice is by no means unnecessary, for there are
many intelligent persons who are unable to indicate true north within
many degrees, though standing on their own doorstep. Having found the
north point as near as you can, look upward about forty degrees from the
horizon, and you will see the lone twinkler called the north or pole
star. Forty degrees is a little less than half-way from the horizon to
the zenith.
By the aid of the map, again, you will be able to find, high up in the
northeast, near the zenith, the large dipper-shaped figure in Ursa
Major, and, when you have once noticed that the two stars in the outer
edge of the bowl of the Dipper point almost directly to the pole-star,
you will have an unfailing means of picking out the latter star
hereafter, when in doubt.[A] Continuing the curve of the Dipper-handle,
in the northeast, your eye will be led to a bright reddish star, which
is Arcturus, in the constellation Booetes.
[A] Let the reader remember that the distance between the two
stars in the brim of the bowl of the Dipper is about ten
degrees, and he will have a measuring-stick that he can
apply in estimating other distances in the heavens.
In the same way you will be able to find the constellations Cassiopeia,
Cepheus, Draco, and Perseus. Don't expect to accomplish it all in an
hour. You may have to devote two or three evenings to such observation,
and make many trips indoors to consult the map, before you have mastered
the subject; but when you have done it you will feel amply repaid for
your exertions, and you will have made for yourself silent friends in
the heavens that will beam kindly upon you, like old neighbors, on
whatever side of the world you may wander.
Having fixed the general outlines and location of the constellations in
your mind, and learned to recognize the chief stars, take your
opera-glass and begin with the constellation Leo and the star Regulus.
Contrive to have some convenient rest for your arms in holding the
glass, and thus obtain not only comfort but steadiness of vision. A
lazy-back chair makes a capital observing-seat. Be very particular, too,
to get a sharp focus. Remember that no two persons' eyes are alike, and
that even the eyes of the same observer occasionally require a change.
In looking for a difficult object, I have sometimes suddenly brought the
sought-for phenomenon into view by a slight turn of the focusing-screw.
You will at once be gratified by the increased brilliancy of the star as
seen by the glass. If the night is clear, it will glow like a diamond.
Yet Regulus, although ranked as a first-magnitude star, and of great
repute among the ancient astrologers, is far inferior in brilliancy to
such stars as Capella and Arcturus, to say nothing of Sirius.
By consulting map No. 2 you will next be able to find the celebrated
star bearing the name of the Greek letter Gamma ([gamma]). If you had a
telescope, you would see this star as a close and beautiful double, of
contrasted colors. But it is optically double, even with an opera-glass.
You can not fail to see a small star near it, looking quite close if the
magnifying power of your glass is less than three times. You will be
struck by the surprising change of color in turning from Regulus to
Gamma--the former is white and the latter deep yellow. It will be well
to look first at one and then at the other, several times, for this is a
good instance of what you will meet with many times in your future
surveys of the heavens--a striking contrast of color in neighboring
stars. One can thus comprehend that there is more than one sense in
which to understand the Scriptural declaration that "one star differeth
from another in glory." The radiant point of the famous November
meteors, which, in 1833 and 1866, filled the sky with fiery showers, is
near Gamma. Turn next to the star in Leo marked Zeta ([zeta]). If your
glass is a pretty large and good one, and your eye keen, you will easily
see three minute companion stars keeping company with Zeta, two on the
southeast, and one, much closer, toward the north. The nearest of the
two on the south is faint, being only between the eighth and ninth
magnitude, and will probably severely test your powers of vision. Next
look at Epsilon ([epsilon]), and you will find near it two
seventh-magnitude companions, making a beautiful little triangle.
[Illustration: MAP 2.]
Away at the eastern end of the constellation, in the tail of the
imaginary Lion, upon whose breast shines Regulus, is the star Beta
([beta]) Leonis, also called Denebola. It is almost as bright as its
leader, Regulus, and you will probably be able to catch a tinge of blue
in its rays. South of Denebola, at a distance of nineteen minutes of
arc, or somewhat more than half the apparent diameter of the moon, you
will see a little star of the sixth magnitude, which is one of the
several "companions" for which Denebola is celebrated. There is another
star of the eighth magnitude in the same direction from Denebola, but at
a distance of less than five minutes, and this you may be able to
glimpse with a powerful field-glass, under favorable conditions. I have
seen it well with a field-glass of 1.6-inch aperture, and a magnifying
power of seven times. But it requires an experienced eye and steady
vision to catch this shy twinkler.
When looking for a faint and difficult object, the plan pursued by
telescopists is to avert the eye from the precise point upon which the
attention is fixed, in order to bring a more sensitive part of the
retina into play than that usually employed. Look toward the edge of the
field of view, while the object you are seeking is in the center, and
then, if it can be seen at all with your glass, you will catch sight of
it, as it were, out of the corner of your eye. The effect of seeing a
faint star in this way, in the neighborhood of a large one, whose rays
hide it from direct vision, is sometimes very amusing. The little star
seems to dart out into view as through a curtain, perfectly distinct,
though as immeasurably minute as the point of a needle. But the instant
you direct your eyes straight at it, presto! it is gone. And so it will
dodge in and out of sight as often as you turn your eyes.
If you will sweep carefully over the whole extent of Leo, whose chief
stars are marked with their Greek-letter names on our little map, you
will be impressed with the power of your glass to bring into sight many
faint stars in regions that seem barren to the naked eye. An opera-glass
of 1.5 aperture will show ten times as many stars as the naked eye can
see.
A word about the "Lion" which this constellation is supposed to
represent. It requires a vivid imagination to perceive the outlines of
the celestial king of beasts among the stars, and yet somebody taught
the people of ancient India and the old Egyptians to see him there, and
there he has remained since the dawn of history. Modern astronomers
strike him out of their charts, together with all the picturesque
multitude of beasts and birds and men and women that bear him company,
but they can not altogether banish him, or any of his congeners, for the
old names, and, practically, the old outlines of the constellations are
retained, and always will be retained. The Lion is the most conspicuous
figure in the celebrated zodiac of Dendera; and, indeed, there is
evidence that before the story of Hercules and his labors was told this
lion was already imagined shining among the stars. It was characteristic
of the Greeks that they seized him for their own, and tried to rob him
of his real antiquity by pretending that Jupiter had placed him among
the stars in commemoration of Hercules's victory over the Nemaean lion.
In the Hebrew zodiac Leo represented the Lion of Judah. It was thus
always a lion that the ancients thought they saw in this constellation.
In the old star-maps the Lion is represented as in the act of springing
upon his prey. His face is to the west, and the star Regulus is in his
heart. The sickle-shaped figure covers his breast and head, Gamma being
in the shoulder, Zeta in the mane of the neck, Mu and Epsilon in the
cheek, and Lambda in the jaws. The fore-paws are drawn up to the breast
and represented by the stars Zi and Omicron. Denebola is in the tuft of
the tail. The hind-legs are extended downward at full length, in the act
of springing. Starting from the star Delta in the hip, the row
consisting of Theta, Iota, Tau, and Upsilon, shows the line of the
hind-legs.
Leo had an unsavory reputation among the ancients because of his
supposed influence upon the weather. The greatest heat of summer was
felt when the sun was in this constellation:
"Most scorching is the chariot of the Sun,
And waving spikes no longer hide the furrows
When he begins to travel with the Lion."
Looking now westwardly from the Sickle of Leo, at a distance about equal
to twice the length of the Sickle, your eye will be caught by a small
silvery spot in the sky lying nearly between two rather faint stars.
This is the famous Praesepe, or Manger, in the center of the
constellation Cancer. The two stars on either side of it are called the
Aselli, or the Ass's Colts, and the imagination of the ancients pictured
them feeding from their silver manger. Turn your glass upon the Manger
and you will see that it consists of a crowd of little stars, so small
and numerous that you will probably not undertake to count them, unless
you are using a large field-glass. Galileo has left a delightful
description of his surprise and gratification when he aimed his
telescope at this curious cluster and other similar aggregations of
stars and discovered what they really were. Using his best instrument,
he was able to count thirty-six stars in the Manger. The Manger was a
famous weather-sign in olden times, and Aratus, in his "Diosemia,"
advises his readers to--
"... watch the Manger: like a little mist
Far north in Cancer's territory it floats.
Its confines are two faintly glimmering stars;
These are two asses that a manger parts,
Which suddenly, when all the sky is clear,
Sometimes quite vanishes, and the two stars
Seem to have closer moved their sundered orbs.
No feeble tempest then will soak the leas;
A murky manger with both stars
Shining unaltered is a sign of rain."
Like other old weather-saws, this probably possesses a gleam of sense,
for it is only when the atmosphere is perfectly transparent that the
Manger can be clearly seen; when the air is thick with mist, the
harbinger of coming storm, it fades from sight.
The constellation Cancer, or the Crab, was represented by the Egyptians
under the figure of a scarabaeus. The observer will probably think that
it is as easy to see a beetle as a crab there. Cancer, like Leo, is one
of the twelve constellations of the Zodiac, the name applied to the
imaginary zone 16 deg. degrees wide and extending completely around the
heavens, the center of which is the ecliptic or annual path of the sun.
The names of these zodiacal constellations, in their order, beginning at
the west and counting round the circle, are: Aries, Taurus, Gemini,
Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricornus, Aquarius,
and Pisces. Cancer has given its name to the circle called the Tropic of
Cancer, which indicates the greatest northerly declination of the sun in
summer, and which he attains on the 21st or 22d of June. But, in
consequence of the precession of the equinoxes, all of the zodiacal
constellations are continually shifting toward the east, and Cancer has
passed away from the place of the summer solstice, which is now to be
found in Gemini.
Below the Manger, a little way toward the south, your eye will be caught
by a group of four or five stars of about the same brightness as the
Aselli. This marks the head of Hydra, and the glass will show a striking
and beautiful geometrical arrangement of the stars composing it. Hydra
is a very long constellation, and trending southward and eastward from
the head it passes underneath Leo, and, sweeping pretty close down to
the horizon, winds away under Corvus, the tail reaching to the eastern
horizon. The length of this skyey serpent is about 100 deg.. Its stars are
all faint, except Alphard, or the Hydra's Heart, a second-magnitude
star, remarkable for its lonely situation, southwest of Regulus. A line
from Gamma Leonis through Regulus points it out. It is worth looking at
with the glass on account of its rich orange-tint.
Hydra is fabled to be the hundred-headed monster that was slain by
Hercules. It must be confessed that there is nothing very monstrous
about it now except its length. The most timid can look upon it without
suspecting its grisly origin.
Coming back to the Manger as a starting-point, look well up to the north
and west, and at a distance somewhat less than that between Regulus and
the Manger you will see a pair of first-magnitude stars, which you will
hardly need to be informed are the celebrated Twins, from which the
constellation Gemini takes its name. The star marked [alpha] in the map
is Castor, and the star marked [beta] is Pollux. No classical reader
needs to be reminded of the romantic origin of these names.
A sharp contrast in the color of Castor and Pollux comes out as soon as
the glass is turned upon them. Castor is white, with occasionally,
perhaps, a suspicion of a green ray in its light. Pollux is deep yellow.
Castor is a celebrated double star, but its components are far too close
to be separated with an opera-glass, or even the most powerful
field-glass. You will be at once interested by the singular _cortege_ of
small stars by which both Castor and Pollux are surrounded. These little
attendant stars, for such they seem, are arrayed in symmetrical
groups--pairs, triangles, and other figures--which, it seems difficult
to believe, could be unintentional, although it would be still more
difficult to suggest any reason why they should be arranged in that way.
[Illustration: MAP 3.]
Our map will show you the position of the principal stars of the
constellation. Castor and Pollux are in the heads of the Twins, while
the row of stars shown in the map Xi ([xi]), Gamma ([gamma]), Nu ([nu]),
Mu ([mu]), and Eta ([eta]), marks their feet, which are dipped in the
edge of the Milky-Way. One can spend a profitable and pleasurable
half-hour in exploring the wonders of Gemini. The whole constellation,
from head to foot, is gemmed with stars which escape the naked eye, but
it sparkles like a bead-spangled garment when viewed with the glass.
Owing to the presence of the Milky-Way, the spectacle around the feet of
the Twins is particularly magnificent. And here the possessor of a good
opera-glass can get a fine view of a celebrated star-cluster known in
the catalogues as 35 M. It is situated a little distance northwest of
the star Eta, and is visible to the naked eye, on a clear, moonless
night, as a nebulous speck. With a good glass you will see two wonderful
streams of little stars starting, one from Eta and the other from Mu,
and running parallel toward the northwest; 35 M is situated between
these star-streams. The stars in the cluster are so closely aggregated
that you will be able to clearly separate only the outlying ones. The
general aspect is like that of a piece of frosted silver over which a
twinkling light is playing. A field-glass brings out more of the
component stars. The splendor of this starry congregation, viewed with a
powerful telescope, may be guessed at from Admiral Smyth's picturesque
description: "It presents a gorgeous field of stars, from the ninth to
the sixteenth magnitude, but with the center of the mass less rich than
the rest. From the small stars being inclined to form curves of three or
four, and often with a large one at the root of the curve, it somewhat
reminds one of the bursting of a sky-rocket." And Webb adds that there
is an "elegant festoon near the center, starting with a reddish star."
No one can gaze upon this marvelous phenomenon, even with the
comparatively low powers of an opera-glass, and reflect that all these
swarming dots of light are really suns, without a stunning sense of the
immensity of the material universe.
It is an interesting fact that the summer solstice, or the point which
the sun occupies when it attains its greatest northerly declination, on
the longest day of the year, is close by this great cluster in Gemini.
In the glare of the sunshine those swarming stars are then concealed
from our sight, but with the mind's eye we can look past and beyond our
sun, across the incomprehensible chasm of space, and behold them still
shining, their commingled rays making our great God of Day seem but a
lonely wanderer in the expanse of the universe.
It was only a short distance southwest of this cluster that one of the
most celebrated discoveries in astronomy was made. There, on the evening
of March 13, 1781, William Herschel observed a star whose singular
aspect led him to put a higher magnifying power on his telescope. The
higher power showed that the object was not a star but a planet, or a
comet, as Herschel at first supposed. It was the planet Uranus, whose
discovery "at one stroke doubled the breadth of the sun's dominions."
The constellation of Gemini, as the names of its two chief stars
indicate, had its origin in the classic story of the twin sons of
Jupiter and Leda:
"Fair Leda's twins, in time to stars decreed,
One fought on foot, one curbed the fiery steed."
Castor and Pollux were regarded by both the Greeks and the Romans as the
patrons of navigation, and this fact crops out very curiously in the
adventures of St. Paul. After his disastrous shipwreck on the island of
Melita he embarked again on a more prosperous voyage in a ship bearing
the name of these very brothers. "And after three months," writes the
celebrated apostle (Acts xxviii, 11) "we departed in a ship of
Alexandria, which had wintered in the isle, whose sign was Castor and
Pollux." We may be certain that Paul was acquainted with the
constellation of Gemini, not only because he was skilled in the learning
of his times, but because, in his speech on Mars Hill, he quoted a line
from the opening stanzas of Aratus's "Phenomena," a poem in which the
constellations are described.
The map will enable you next to find Procyon, or the Little Dog-Star,
more than twenty degrees south of Castor and Pollux, and almost directly
below the Manger. This star will interest you by its golden-yellow color
and its brightness, although it is far inferior in the latter respect to
Sirius, or the Great Dog-Star, which you will see flashing splendidly
far down beneath Procyon in the southwest. About four degrees northwest
of Procyon is a third-magnitude star, called Gomelza, and the glass will
show you two small stars which make a right-angled triangle with it, the
nearer one being remarkable for its ruddy color.
Procyon is especially interesting because it is attended by an invisible
star, which, while it has escaped all efforts to detect it with powerful
telescopes, nevertheless reveals its presence by the effect of its
attraction upon Procyon. It is a curious fact that both of the so-called
Dog-Stars are thus attended by obscure or dusky companion-stars, which,
notwithstanding their lack of luminosity, are of great magnitude. In the
case of Sirius, the improvement in telescopes has brought the mysterious
attendant into view, but Procyon's mate remains hidden from our eyes.
But it can not escape the ken of the mathematician, whose penetrating
mental vision has, in more than one instance, outstripped the
discoveries of the telescope. Almost half a century ago the famous
Bessel announced his conclusion--in the light of later developments it
may well be called discovery--that both Sirius and Procyon were binary
systems, consisting each of a visible and an invisible star. He
calculated the probable period of revolution, and found it to be, in
each case, approximately fifty years. Sixteen years after Bessel's
death, one of Alvan Clark's unrivaled telescopes at last revealed the
strange companion of Sirius, a huge body, half as massive as the giant
Dog-Star itself, but ten thousand times less brilliant, and more recent
observations have shown that its period of revolution is within six or
seven months of the fifty years assigned by Bessel. If some of the
enormous telescopes that have been constructed in the past few years
should succeed in rendering Procyon's companion visible also, it is
highly probable that Bessel's prediction would receive another
substantial fulfillment.
The mythological history of Canis Minor is somewhat obscure. According
to various accounts it represents one of Diana's hunting-dogs, one of
Orion's hounds, the Egyptian dog-headed god Anubis, and one of the dogs
that devoured their master Actaeon after Diana had turned him into a
stag. The mystical Dr. Seiss leaves all the ancient myth-makers far in
the rear, and advances a very curious theory of his own about this
constellation, in his "Gospel in the Stars," which is worth quoting as
an example of the grotesque fancies that even in our day sometimes
possess the minds of men when they venture beyond the safe confines of
this terraqueous globe. After summarizing the various myths we have
mentioned, he proceeds to identify Procyon, putting the name of the
chief star for the constellation, "as the starry symbol of those
heavenly armies which came forth along with the King of kings and Lord
of lords to the battle of the great day of God Almighty, to make an end
of misrule and usurpation on earth, and clear it of all the wild beasts
which have been devastating it for these many ages."
The reader will wonder all the more at this rhapsody after he has
succeeded in picking out the modest Little Dog in the sky.
Sirius, Orion, Aldebaran, and the Pleiades, all of which you will
perceive in the west and southwest, are generally too much involved in
the mists of the horizon to be seen to the best advantage at this
season, although it will pay you to take a look through the glass at
Sirius. But the splendid star Capella, in the constellation Auriga, may
claim a moment's attention. You will find it high up in the northwest,
half-way between Orion and the pole-star, and to the right of the Twins.
It has no rival near, and its creamy-white light makes it one of the
most beautiful as well as one of the most brilliant stars in the
heavens. Its constitution, as revealed by the spectroscope, resembles
that of our sun, but the sun would make but a sorry figure if removed to
the side of this giant star. About seven and a half degrees above
Capella, and a little to the left, you will see a second-magnitude star
called Menkalina. Two and a half times as far to the left, or south, in
the direction of Orion, is another star of equal brightness to
Menkalina. This is El Nath, and marks the place where the foot of
Auriga, or the Charioteer, rests upon the point of the horn of Taurus.
Capella, Menkalina, and El Nath make a long triangle which covers the
central part of Auriga. The naked eye shows two or three misty-looking
spots within this triangle, one to the right of El Nath, one in the
upper or eastern part of the constellation, near the third-magnitude
star Theta ([theta]), and another on a line drawn from Capella to El
Nath, but much nearer to Capella. Turn your glass upon these spots, and
you will be delighted by the beauty of the little stars to whose united
rays they are due.
El Nath has around it some very remarkable rows of small stars, and the
whole constellation of Auriga, like that of Gemini, glitters with
star-dust, for the Milky-Way runs directly through it.
With a powerful field-glass you may try a glimpse at the rich
star-clusters marked 38 M, 37 M, and 33^7.
[Illustration: MAP 4.]
The mythology of Auriga is not clear, but the ancients seem to have been
of one mind in regarding the constellation as representing the figure of
a man carrying a goat and her two kids in his arms. Auriga was also
looked upon as a beneficent constellation, and the goat and kids were
believed to be on the watch to rescue shipwrecked sailors. As Capella,
which represents the fabled goat, shines nearly overhead in winter, and
would ordinarily be the first bright star to beam down through the
breaking clouds of a storm at that season, it is not difficult to
imagine how it got its reputation as the seaman's friend. Dr. Seiss has
so spirited a description of the imaginary figure contained in this
constellation that I can not refrain from quoting it:
"The figure itself is that of a mighty man seated on the Milky-Way,
holding a band or ribbon in his right hand, and with his left arm
holding up on his shoulder a she-goat which clings to his neck and looks
out in astonishment upon the terrible bull; while in his lap are two
frightened little kids which he supports with his great hand."
It is scarcely necessary to add that Dr. Seiss insists that Auriga, as a
constellation, was invented long before the time of the Greeks, and was
intended prophetically to represent that Good Shepherd who was to come
and rescue the sinful world.
If any reader wishes to exercise his fancy by trying to trace the
outlines of this figure, he will find the head of Auriga marked by the
star Delta ([delta]) and the little group near it. Capella, in the heart
of the Goat, is just below his left shoulder, and Menkalina marks his
right shoulder. El Nath is in his right foot, and Iota ([iota]) in his
left foot. The stars Epsilon ([epsilon]), Zeta ([zeta]), Eta ([eta]),
and Lambda ([lambda]) shine in the kids which lie in Auriga's lap. The
faint stars scattered over the eastern part of the constellation are
sometimes represented as forming a whip with many lashes, which the
giant flourishes with his right hand.
Let us turn back to Denebola in the Lion's Tail. Now glance from it down
into the southeast, and you will see a brilliant star flashing well
above the horizon. This is Spica, the chief twinkler of Virgo, and it is
marked on our circular map. Then look into the northwest, and at about
the same distance from Denebola, but higher above the horizon than
Spica, you will catch the sparkling of a large, reddish star. It is
Arcturus in Booetes. The three, Denebola, Spica, and Arcturus, mark the
corners of a great equilateral triangle. Nearly on a line between
Denebola and Arcturus, and somewhat nearer to the former, you will
perceive a curious twinkling, as if gossamers spangled with dew-drops
were entangled there. One might think the old woman of the nursery rhyme
who went to sweep the cobwebs out of the sky had skipped this corner, or
else that its delicate beauty had preserved it even from her housewifely
instincts. This is the little constellation called Berenice's Hair. Your
opera-glass will enable you to count twenty or thirty of the largest
stars composing this cluster, which are arranged, as so often happens,
with a striking appearance of geometrical design. The constellation has
a very romantic history. It is related that the young Queen Berenice,
when her husband was called away to the wars, vowed to sacrifice her
beautiful tresses to Venus if he returned victorious over his enemies.
He did return home in triumph, and Berenice, true to her vow, cut off
her hair and bore it to the Temple of Venus. But the same night it
disappeared. The king was furious, and the queen wept bitterly over the
loss. There is no telling what might have happened to the guardians of
the temple, had not a celebrated astronomer named Conon led the young
king and queen aside in the evening and showed them the missing locks
shining transfigured in the sky. He assured them that Venus had placed
Berenice's lustrous ringlets among the stars, and, as they were not
skilled in celestial lore, they were quite ready to believe that the
silvery swarm they saw near Arcturus had never been there before. And so
for centuries the world has recognized the constellation of Berenice's
Hair.
Look next at Corvus and Crater, the Crow and the Cup, two little
constellations which you will discover on the circular map, and of which
we give a separate representation in Map 5. You will find that the stars
Delta ([delta]) and Eta ([eta]), in the upper left-hand corner of the
quadrilateral figure of Corvus, make a striking appearance. The little
star Zeta ([zeta]) is a very pretty double for an opera-glass. There is
a very faint pair of stars close below and to the right of Beta
([beta]). This forms a severe test. Only a good opera-glass will show
these two stars as a single faint point of light. A field-glass,
however, will show both, one being considerably fainter than the other.
Crater is worth sweeping over for the pretty combinations of stars to be
found in it.
You will observe that the interminable Hydra extends his lengthening
coils along under both of the constellations. In fact, both the Cup and
the Crow are represented as standing upon the huge serpent. The outlines
of a cup are tolerably well indicated by the stars included under the
name Crater, but the constellation of the Crow might as well have borne
any other name so far as any traceable likeness is concerned. One of the
legends concerning Corvus avers that it is the daughter of the King of
Phocis, who was transformed into a crow to escape the pursuit of
Neptune. She is certainly safe in her present guise.
Arcturus and Spica, and their companions, may be left for observation to
a more convenient season, when, having risen higher, they can be studied
to better advantage. It will be well, however, to merely glance at them
with the glass in order to note the great difference of color--Spica
being brilliantly white and Arcturus almost red.
[Illustration: MAP 5.]
We will now turn to the north. You have already been told how to find
the pole-star. Look at it with your glass. The pole-star is a famous
double, but its minute companion can only be seen with a telescope. As
so often happens, however, it has another companion for the opera-glass,
and this latter is sufficiently close and small to make an interesting
test for an inexperienced observer armed with a glass of small power. It
must be looked for pretty close to the rays of the large star, with such
a glass. It is of the seventh magnitude. With a large field-glass
several smaller companions may be seen, and a very excellent glass may
show an 8.5-magnitude star almost hidden in the rays of the
seventh-magnitude companion.
With the aid of map No. 6 find in Ursa Minor, which is the
constellation to which the pole-star belongs, the star Beta ([beta]),
which is also called Kochab (the star marked [alpha] in the map is the
pole-star). Kochab has a pair of faint stars nearly north of it, about
one degree distant. With a small glass these may appear as a single
star, but a stronger glass will show them separately.
[Illustration: MAP 6.]
And now for Ursa Major and the Great Dipper--Draco, Cepheus, Cassiopeia,
and the other constellations represented on the circular map, being
rather too near the horizon for effective observation at this time of
the year. First, as the easiest object, look at the star in the middle
of the handle of the Dipper (this handle forms the tail of Ursa Major),
and a little attention will show you, without the aid of a glass, if
your eye-sight is good, that the star is double. A smaller star seems to
be almost in contact with it. The larger of these two stars is called
Mizar and the smaller Alcor--the Horse and his Rider the Arabs said.
Your glass will, of course, greatly increase the distance between Alcor
and Mizar, and will also bring out a clear difference of color
distinguishing them. Now, if you have a very powerful glass, you may be
able to see the Sidus Ludovicianum, a minute star which a German
astronomer discovered more than a hundred and fifty years ago, and,
strangely enough, taking it for a planet, named it after a German
prince. The position of the Sidus Ludovicianum, with reference to Mizar
and Alcor, is represented in the accompanying sketch. You must look very
sharply if you expect to see it, and your opera-glass will have to be a
large and strong one. A field-glass, however, can not fail to show it.
Sweep along the whole length of the Dipper's handle, and you will
discover many fine fields of stars. Then look at the star Alpha
([alpha]) in the outer edge of the bowl nearest to the pole-star. There
is a faint star, of about the eighth magnitude, near it, in the
direction of Beta ([beta]). This will prove a very difficult test. You
will have to try it with averted vision. If you have a field-glass,
catch it first with that, and, having thus fixed its position in your
mind, try to find it with the opera-glass. Its distance is a little over
half that between Mizar and Alcor. It is of a reddish color.
You will notice nearly overhead three pairs of pretty bright stars in a
long, bending row, about half-way between Leo and the Dipper. These mark
three of Ursa Major's feet, and each of the pairs is well worth looking
at with a glass, as they are beautifully grouped with stars invisible to
the naked eye. The letters used to designate the stars forming these
pairs will be found upon our map of Ursa Major. The scattered group of
faint stars beyond the bowl of the Dipper forms the Bear's head, and you
will find that also a field worth a few minutes' exploration.
[Illustration: MIZAR, ALCOR, AND THE SIDUS LUDOVICIANUM.]
The two bears, Ursa Major and Ursa Minor, swinging around the pole of
the heavens, have been conspicuous in the star-lore of all ages.
According to fable, they represent the nymph Calisto, with whom Jupiter
was in love, and her son Arcas, who were both turned into bears by Juno,
whereupon Jupiter, being unable to restore their form, did the next best
thing he could by placing them among the stars. Ursa Major is Calisto,
or Helica, as the Greeks called the constellation. The Greek name of
Ursa Minor was Cynosura. The use of the pole-star in navigation dates
back at least to the time of the Phoenicians. The observer will note
the uncomfortable position of Ursa Minor, attached to the pole by the
end of its long tail.
But, after all, no one can expect to derive from such studies as these
any genuine pleasure or satisfaction unless he is mindful of the real
meaning of what he sees. The actual truth seems almost too stupendous
for belief. The mind must be brought into an attitude of profound
contemplation in order to appreciate it. From this globe we can look out
in every direction into the open and boundless universe. Blinded and
dazzled during the day by the blaze of that star, of which the earth is
a near and humble dependent, we are shut in as by a curtain. But at
night, when our own star is hidden, our vision ranges into the depths of
creation, and we behold them sparkling with a multitude of other suns.
With so simple an aid as that of an opera-glass we penetrate still
deeper into the profundities of space, and thousands more of these
strange, far-away suns come into sight. They are arranged in pairs,
sets, rows, streams, clusters--here they gleam alone in distant
splendor, there they glow and flash in mighty swarms. This is a look
into heaven more splendid than the imagination of Bunyan pictured; here
is a celestial city whose temples are suns, and whose streets are the
pathways of light.