THE FIXED STARS.
FIXED STARS—MAGNITUDE OF THE STARS—CONSTELLATIONS—DESCRIPTIONS OF THE
ZODIACAL CONSTELLATIONS—NORTHERN AND SOUTHERN STAR GROUPS—DISTANCE OF
STARS.
We have been considering the planets so far as they are known to
astronomers, but no doubt we shall find out others some day beyond
Neptune in space, for it must be assumed that there are other planets
wandering about in the infinite firmament. At present, however, we
cannot spare time for such speculation; we have got to peep at the
stars and their groupings.
“What little bits of things the stars are,” a child said once in our
hearing; and there were others present who were inclined to believe
that the tiny light spots we could see looked small—not because they
were distant, but because they were of no great magnitude; and when
those children were told that the tiny stars were “suns” like our sun,
giving heat and light millions and millions of miles away,—and, so far
as we can tell, some are much bigger and hotter than our own sun,—they
were very much surprised indeed, and one little girl aptly quoted Dr.
Watts:—
“Twinkle, twinkle, little star,
How I wonder what you are”!
Now let us endeavour to learn something about these apparently tiny
specks, and why they “twinkle.”
At a very early period in the history of astronomy the observers
of the heavens grouped stars together in fancied resemblances to
men or animals; and these “constellations,” as they are termed, are
combinations of _fixed stars_—that is, of stars which do not wander
about as the planets do. But these so-called fixed stars have motions;
they are only relatively fixed with reference to their positions to
each other as they appear to revolve daily round the earth. But stars
have a movement of their own, which is termed their “proper motion.”
It is to Halley that the discovery of these real star motions is due.
He saw three very bright stars (Sirius, Aldebaran, and Arcturus) were
not in the places they had been assigned. The sun also has been found
to possess a “proper motion,” and, with the planets, is travelling
as determined by Sir J. Herschel, to a particular place in the
constellation called Hercules. There are now star catalogues and star
maps, for the heavens have been as closely surveyed as the earth,
and by accurate observations it has now become possible to find the
position of every star usually visible. Some of the stars are used as
“clock” stars, by which sidereal time can be calculated accurately, and
the clocks thereby corrected. The stars, though termed “fixed,” are in
perpetual movement—Arcturus at the rate of fifty miles a second, and
others less. Only the rates of a few are known.
The number of the stars is beyond our calculation, and even the
number of stars only visible in the telescope amount to millions, and
these are called telescopic stars. The visible stars amount to about
six thousand, and of course these are the brightest up to the sixth
magnitude. There are more visible in the southern than in the northern
hemisphere. The magnitudes of the stars range in classes according to
the brightness of the stars observed, for this is really the test from
the first magnitude to the sixth; after that the telescopic stars are
seen up to the fifteenth or sixteenth. We can only see about three
thousand stars at any one time from any place, although, as remarked
above, many millions may be observed with a good telescope, and as many
more, probably twenty millions, are invisible.
We will now proceed to detail the constellations, which are familiar
by name to everybody. We have already given the names of the zodiacal
groups, which consist of many stars, each designated by a letter of the
Greek alphabet so far as possible, then the Roman letters and numerals
are employed. Thus α (Alpha) is the most brilliant star; β (Beta) the
next bright γ (Gamma) the next, and so on; so the relative brilliancy
of the stars in the constellation is indicated, but not the very
biggest star of the first magnitude is intended by α, for the star δ in
one constellation may equal α in another. John Bayer originated this
method in 1603.
The arrangement of the constellations is plunged in the obscurity
of ages, but B.C. 370 there were forty-five thus grouped. There are
northern and southern constellations which are visible above our old
friends Aries, Taurus, Cancer, etc. We will, as in duty bound, consider
our old acquaintances first, and then give a list of the northern and
southern groups of stars; but we shall find that the forms are in the
greater part due to the imagination of the ancients, and do not bear
out our ideas of the animals they are supposed to represent, while at
the same time they cross and recross with other constellations in the
skies in a very puzzling way.
[Illustration: Fig. 596.—Aries.]
The first constellation is ARIES, the Ram, which is celebrated in
mythology as the proud possessor of the Golden Fleece, which we may
remember was seized and carried away by Jason and the Argonauts. The
Hellespont is so called from Helle, who fell from the Ram’s back when
being carried upon it over the Black Sea. The Ram is here represented
with the equinoctial ring.
We perceive in Aries two very bright stars near the head. These are
(α) Arietis and (γ) Sheretan. The signs and constellations do not now
correspond as they used to do, because of the change in the position of
the stars, which gives rise to the Precession of the Equinoxes (_vide
ante._, p. 497), so that the stars which two thousand years ago were
in conjunction with the sun, are much more to the eastward. In olden
time (when astronomy was young), the sun entered Aries on the 21st
March, and now a change has taken place. But in about another twenty
thousand years, they will all come right again. This will be perceived
by reference to the celestial globe. The Ram has sixty-six stars in his
constitution.
TAURUS, the Bull, is the next constellation. He received his name from
the celebrated animal into which Jupiter transformed himself when he
wished to carry away Europa. The star Aldebaran (α) is the end of a
kind of V in the Bull’s face. The Pleiades are on the shoulder to
the right. This cluster of twinkling stars is well known, and will
guide the observer towards the imaginary Bull, which we must nowadays
describe as rather a fanciful delineation. Europe is called after
Europa, because Jupiter, as a Bull, carried her to this continent.
There are 141 stars in Taurus, according to the number found in the
list of Aratus, and probably more.
[Illustration: Fig. 597.—Taurus.]
GEMINI, the Twins, which are supposed to be Castor and Pollux, though
it is believed that two goats were the original sign—which statement,
taken in connection with the ram and the bull, that were also turned
out in the spring-time, may have something to recommend it. But now
Castor and Pollux are generally recognized as the constellation. During
the expedition for the Golden Fleece, the electric appearance, now
known as St. Elmo’s Fire, became visible upon them, and their effigies
were placed in the forepart of ships as a good omen. This led to the
adoption of the “figure-head.” They were made into stars when Pollux
was immortalized by Jupiter, for he divided the boon with his brother.
The planet Uranus was discovered near this constellation, which
contains eighty-five stars.
[Illustration: Fig. 598.—Gemini.]
CANCER, the Crab, is the next in order, and the only derivation we
can find for this is that Juno sent a crab to attack Hercules when he
was busily engaged with the many-headed Hydra. The crab was directed
to pinch the hero’s foot, but it appears rather a lame device for
the Queen to adopt. The crab, however, was killed by Hercules, and
placed amongst the stars by Juno as a reward; so he gained immortality
cheaply. He, Cancer, contains more than eighty stars, but none of them
of any particular note. Some writers explain the sign as reminding the
ancients of “the retrograde movement of the sun to the north”; but as
a crab does not move “backwards,” we will still adhere to mythology
as equally satisfactory at any rate. Cancer, however, was termed the
“northern gate of the sun.”
[Illustration: Fig. 599.—Cancer.]
The next is LEO, the Lion, which came round in summer and at the period
of much heat, so this fierce animal may have been chosen to represent
that season. But mythology will have us credit the Nemæan Lion sent
against Hercules by Juno as the origin of this constellation. The lion
was, like the crab, placed amongst the stars when he was killed. He is
a very brilliant constellation, and a very bright star called Regulus
is to be seen in his chest—“Cor Leonis.” Another very fine star of
the second magnitude is observable in the tail. The Lion consists of
ninety-five stars, the principal ones being of the first and second
magnitudes.
[Illustration: Fig. 600.—Leo.]
VIRGO is supposed to be outlined by a very rich cluster of stars,
and one of the first magnitude. The Virgin is by some supposed to
be Astræa, the goddess, but is more likely referable to a girl
gleaning, or holding an ear of corn in semblance of the harvest. This
constellation contains more than one hundred stars. One of them in the
wheat-ear is a particularly brilliant one, and noted for its “solitary
splendour,” as no star of large magnitude is near it. The Arabs used to
call it the Solitary Simak; _Spica Virginis_ is the modern name.
[Illustration: Fig. 601.—Virgo.]
LIBRA, which follows, may either indicate the balance, or scales
of justice, of Astræa, or the equal day and night at the autumnal
equinox. Virgil mentions Astræa’s balance, and thus we have a classical
authority for the very mythological view of the two foregoing
constellations. Libra is not very distinct; it contains fifty-one
stars, four of which are very bright.
[Illustration: Fig. 602.—Libra.]
SCORPIO, the Scorpion, according to classical writers, encountered
Orion, who is also met with in the stellar universe. The scorpion stung
Orion because he declared there was no living creature he could not
overcome by force. On the other hand, this sign may have some reference
to the unhealthy time of year, and the prevalence of disease about the
time that _Scorpio_ appeared. A beautiful star of reddish hue and of
the first magnitude is prominent amongst the brilliant assembly of the
Scorpion’s forty-four stars.
[Illustration: Fig. 603.—Scorpio.]
SAGITTARIUS, the Archer, is, as one can see, a Centaur, and said to be
Chiron, who was wounded by Hercules, and cured by being taken up to
Heaven by Jupiter. This Chiron is represented as a great patron of the
arts, and thus the fable may be said to exemplify the proverb, “Art
is long, time is fleeting”; for readers of mythology will find much
more in the legends than is apparent on the surface. But we can now
only regard the Centaur from an astronomical, and not a philosophical
standpoint. Sagittarius has no very brilliant stars. He is close to the
Milky Way, and contains sixty-nine stars, five forming a sort of V in
the bow, sometimes compared to a ladle or “dipper.”
[Illustration: Fig. 604.—Sagittarius.]
[Illustration: Fig. 605.—Capricornus.]
CAPRICORNUS, the Goat, is supposed to be _Pan_—“the great god Pan,” who
turned himself into a goat. The sun was in Capricornus at mid-winter,
so the “southern gate of the sun” was a title bestowed upon him. But
now the constellation is later. It does not include any very striking
stars, of which there are fifty-one in the “Goat.”
AQUARIUS, or the Waterbearer, may have referred to wet weather, or as
others declare, to Ganymede, the Cupbearer. There are four stars in the
waterpot like a Y; and more than one hundred stars of small brilliancy
are included in this constellation. But here again fancy must come to
our assistance, for without a diagram the ordinary observer could not
distinguish the Waterbearer.
[Illustration: Fig. 607.—Aquarius.]
PISCES, the Fishes, are not plainly defined. It is supposed that Venus
and Cupid turned themselves into fish when the Titans assailed Heaven.
This Constellation occupies a triangle in the sky.
[Illustration: Fig. 606.—Pisces.]
The foregoing are the zodiacal constellations, and may be more easily
remembered by repeating an old rhyme, which runs as follows:—
“The Ram, the Bull, the Heavenly Twins;
Then, next the Crab, the Lion shines,
The Virgin, and the Scales;
The Scorpion, Archer, and the Goat,
The Man who holds the Watering Pot,
The Fish with Glittering tails.”
The arrangement of the various Constellations at which we have so
rapidly glanced, as well as of those that follow, has been the work of
many different periods. Aratus and Ptolemy are the oldest enumerators,
but modern research has added immensely to the store of knowledge.
Many of the most prominent stars were named by Grecian and Arabian
observers, and many of the names are still retained—such as Arcturus,
Rigel, Capella, and others.
THE NORTHERN CONSTELLATIONS.
There are, altogether, thirty-five of these, as per list on next page.
It is of course impossible to describe them all, but we will make a
few remarks respecting those which will be distinguished most readily,
and the manner of finding out particular stars. There are star maps
published, and with a little attention and reading, a great many very
pleasant evening excursions may be made across the sky, with or without
a telescope. The following is the list of the northern constellations.
We have put them in various types to indicate the most important.
+----------------------------------------------+-------------+--------+
| | | NO. OF |
| NAME OF CONSTELLATION. | “AUTHOR.” | STARS. |
+----------------------------------------------+-------------+--------+
| URSA MAJOR The Great Bear | Aratus | 87 |
| _Ursa Minor_ The Lesser Bear | “ | 24 |
| _Perseus_ Perseus | “ | 59 |
| _Auriga_ The Waggoner | “ | 66 |
| _Boötes_ The Herdsman (Boötes) | “ | 54 |
| _Draco_ The Dragon | “ | 80 |
| _Cepheus_ Cepheus | “ | 35 |
| _Canes Venatici_ {The Greyhounds} | Hevelius | 25 |
| {Hunting Dogs } | | |
| _Cor Caroli_ Heart of Charles | Halley | 3 |
| _Triangulum_ The Triangle | Aratus | 16 |
| Triangulum Minor The Little Triangle | Hevelius | 10 |
| Musca The Fly | Bode | 6 |
| Lynx The Lynx | Hevelius | 44 |
| Leo Minor The Lesser Lion | “ | 53 |
| Coma Berenices Berenice’s Hair | Tycho Brahé | 43 |
| _Camelopardalis_ The Giraffe | Hevelius | 58 |
| Mons Menelaus Mount Menalaus | “ | 11 |
| _Corona Borealis_ The Northern Crown | Aratus | 21 |
| _Serpens_ The Serpent | “ | 64 |
| Scutum Sobieski Sobieski’s Shield. | Hevelius | 8 |
| _Hercules_ Hercules | Aratus | 113 |
| _Serpentarius_ The Serpent-bearer | “ | 74 |
| Taurus Poniatowski Poniatowski’s Bull | Poczobat | 7 |
| LYRA The Harp, or Lyre | Aratus | 22 |
| _Vulpecula et Anser_ Fox and Goose | Hevelius | 37 |
| _Sagitta_ The Arrow | Aratus | 18 |
| AQUILA The Eagle | “ | 71 |
| _Delphinus_ The Dolphin | “ | 18 |
| _Cygnus_ The Swan | “ | 81 |
| CASSIOPEIA The Lady’s Chair | “ | 55 |
| _Equuleus_ The Little Horse | Ptolemy | 10 |
| Lacerta The Lizard | Hevelius | 16 |
| _Pegasus_ Pegasus (Flying Horse) | Aratus | 89 |
| _Andromeda_ Andromeda | “ | 66 |
| Tarandus The Reindeer | Lemounier | 12 |
| (There are a few others marked in continental maps.) | |
+----------------------------------------------+-------------+--------+
The GREAT BEAR, or “Charles’s Wain,” or the “Plough,” as Ursa Major
is variously called, is of great value in indicating the pole star,
which, when once known, can never be mistaken. This constellation has
also been termed the “Dipper,” and is very conspicuous in the northern
hemisphere. The three stars form the bear’s tail, or the handle of the
“plough”; the others form the body, Charles’s Wain, or “Karl-Wagen,”
the German term for peasant’s cart, is represented by the quadrangle
forming the cart, and the other three stars are the horses.
The “Pointers” are the two end stars, and if a line be followed
northwards from them it will lead close to _Polaris_, the principal
star in the lesser bear. This pole star is of a very great brightness,
and peeps out, almost isolated, with a pure lustre. The names of the
pointers are Dubhe and Menak. The star at the tail-tip is Benetnasch,
then Mizar and Alioth. Megrez and Phad are the remaining pair. We
append a rough outline of the bear, for the information of those who
have not yet noticed it.
The Lesser Bear is not so important as his elder brother as regards
size, but he is very useful to astronomers. He resembles the Great
Bear in appearance, but is smaller, and the positions of the stars
are inverted. In the cut on page 555 (fig. 629) you see the little
bear swinging round the polar star, which is at the tip of the Lesser
Bear’s tail, so any one will be enabled to find him if they look for
the polar star, and then count the three stars away from it, and the
four in the body. The Great Bear’s tail points in the other direction.
This movement of the earth’s axis by displacing the equinoctial points,
alters the “declination” and “right ascension” of the stars (compare
page 473). So Polaris is gradually approaching the actual polar point.
In about 200 years he will have got as close as he can, and will then
begin to recede from it, and in about 12,500 years after he will reach
his most distant point.
[Illustration: Fig. 608.—The Great Bear.]
POLARIS, the Pole Star, was called “Cynosure” by the ancients, and thus
we can understand the quotation, “Cynosure of neighbouring eyes,” when
a person or object is very attractive. The pole star was the point to
which all looked. There are some other very important stars in these
constellations. For instance, in—
Perseus we have Algenib and Algol, of second magnitude.
Auriga we have Capella, of the first magnitude.
Boötes we have Arcturus, of the first magnitude.
Lyra we have Vega, a very large and bright star.
Aquila, Altair, also a very beautiful star.
In Cygnus there is Deneb, of the first magnitude.
These stars are also designated by the Greek letters—α, lyræ, or the
first in the Lyre—that is, Vega; and so on for all, according to rank,
as already explained.
SOUTHERN CONSTELLATIONS.
We must pass on to the southern constellations, of which there are
forty-six; the principal ones are in capital letters:—
+---------------------------------------------------+-----------+--------+
| | | NO. OF |
| NAME OF CONSTELLATION. | “AUTHOR.” | STARS. |
+---------------------------------------------------+-----------+--------+
| * Phœnix The Phœnix | Bayer | 13 |
| Apparatus Sculptoris The Sculptor’s Tools | Lacaille | 12 |
| _Eridanus Fluvius_ The River Po | Aratus | 84 |
| * Hydrus The Water-snake | Bayer | 10 |
| _Cetus_ The Whale | Aratus | 97 |
| Fornax Chemica The Furnace | Lacaille | 14 |
| * Horologium The Clock | “ | 12 |
| * Rheticulus Rhomboidialus The Rhomboidal Net | “ | 10 |
| * Xiphias Dorado The Sword-fish | Bayer | 7 |
| * Celapraxitels The Engraver’s Tools | Lacaille | 16 |
| _Lepus_ The Hare | Aratus | 19 |
| Columba Noachi Noah’s Dove | Halley | 10 |
| ORION Orion | Aratus | 78 |
| _Argo Navis_ The ship Argo | “ | 64 |
| CANIS MAJOR The Great Dog | “ | 31 |
| Equuleus Pictoris The Easel | Lacaille | 8 |
| _Monoceros_ The Unicorn | Hevelius | 31 |
| _Canis Minor_ The Lesser Dog | Ptolemy | 14 |
| * Chameleon The Chameleon | Bayer | 10 |
| Pyxis Nautica The Mariner’s Compass | Lacaille | 4 |
| * Piscis Volans The Flying Fish | Bayer | 8 |
| Hydra The Snake | Aratus | 60 |
| Sextans The Sextant | Hevelius | 41 |
| * Rober Carolinum Charlie’s Oak | Halley | 12 |
| Antlia Pneumatica The Air Pump | Lacaille | 3 |
| _Crater_ The Cup | Aratus | 31 |
| _Corvus_ The Crow | “ | 9 |
| *_Crux Australis_ The Southern Cross | Royer | 6 |
| Apis Musca The South Fly | Bayer | 4 |
| * Avis Indica The Bird of Paradise | “ | 11 |
| * Circinus The Compass | Lacaille | 4 |
| _Centaurus_ The Centaur | Aratus | 35 |
| _Lupus_ The Wolf | “ | 24 |
| Norma The Square | Lacaille | 12 |
| * Triangulum Australis The Southern Triangle | Bayer | 5 |
| *_Ara_ The Altar | Aratus | 9 |
| * Telescopium The Telescope | Lacaille | 9 |
| _Corona Australis_ The Southern Crown | Ptolemy | 12 |
| * Pavo The Peacock | Bayer | 14 |
| * Indus The Indian | “ | 12 |
| Microscopium The Microscope | Lacaille | 10 |
| * Octans Hadliensis Hadley’s Octant | “ | 43 |
| * Grus The Crane | Bayer | 14 |
| Toucan The Toucan | “ | 9 |
| _Pisces Australis_ The Southern Fish | Aratus | 24 |
| * Mons Mensa Table Mountain | Lacaille | 30 |
+---------------------------------------------------+-----------+--------+
We need only describe Orion and Canis Major, the principal groups. The
former certainly constitutes the most glorious group, and it is visible
to all the world, because the equinoctial passes through it.
ORION, as we have said, can be viewed from either hemisphere, and so
can some others; but those marked with an asterisk in the foregoing
list are not visible in the latitude of London.
[Illustration: Fig. 609.—Orion.]
Orion is a very brilliant constellation, and contains two fine stars of
the first magnitude, and some of the second. The former are Betelgeux
and Rigel. Bellatrix is the third in order. The “belt” is formed of
three bright stars, and the sword is visible as five stars just below.
Canis Major possesses Sirius, a very fine star (the dog star). Canis
Minor has two of the first and second magnitude, and Hydra has one of
the first. The Southern Cross is a beautiful constellation, invisible
in our latitude, but familiar to sailors in the Southern Seas.
THE STARS’ DISTANCE AND MAGNITUDE.
[Illustration: Fig. 610.—Polaris.]
When we gaze up into the sky at night, we see the stars twinkling far
away, and we may remark here that this twinkling of the stars is due
to the atmosphere and the changes in its power of refraction, and of
course the star’s light changes its direction. But if we ascend in a
balloon into very high and rarefied strata of the air, we will find
the twinkling less. We have given the number of the stars according
to Flamstead, but the larger the telescope the greater will be the
number of stars we shall see, numbers again being too far even for our
perfected instruments.
But we can gain some idea of the magnitude of the stars when we
consider the distance to arrive at, which is a most difficult task, for
figures seem scarcely long enough to count the millions of miles, and
no instrument can detect the parallax. Even supposing the parallax to
be a very small fraction of a degree we should get a result equalling
trillions of miles. NO. 61 in Cygni was at one time continually
observed by Professor Bessel, and he found that its distance—and it is
the nearest star—is _sixty-two and a half trillions of miles_.
[Illustration: Fig. 611.—The Southern Cross.]
Let us consider what this means. Light comes to us from the sun
(91,000,000 of miles) in about eight minutes, and travels at the
rate of something like 186,000 miles in a second. But even at that
astounding rate the light from the star called 61 Cygni took ten
years to reach the earth; and there are stars whose light has never
yet reached the earth, although the gleam may have been travelling at
186,000 miles a second for thousands of years. And we may presume that
though we still see the light of stars, some of them may be dead, but
the light left is still progressing to us through space.
So we must conclude that some stars which look large, as do Vega and
Sirius for instance, must be enormous “suns,” a great deal larger than
our sun, and the stars are each the centre of invisible systems just
as our sun is the centre of the “solar” system. Vega is a tremendous
star, and shines with her own light as do all other visible stars; for
reflected light, so very visible in the moon, which is close to us,
would be quite invisible at such tremendous distances. So we must call
these stars “suns,” and may add an apparently astonishing fact, that
our own sun is merely one of the stars in the Galaxy, or “Milky Way”!