A Field Book of the Stars Part 7

Owing to precession, ?, , and a Cephei will be successively the Pole Star in 4500, 6000, and 7500 A.D. respectively.

d is a double whose components are yellow and blue. It is an interesting variable changing from magnitude 3.7 to 4.9 at intervals of 5 days 8 hours 47 minutes. As it is three times as bright at maximum as at minimum and can be observed with the naked eye its variations are well worth observing.

[Ill.u.s.tration: CEPHEUS]

PEGASUS (peg-a-sus)--THE WINGED HORSE. (Face South.)

LOCATION.--One corner of the Great Square is found by drawing a line from Polaris to Ca.s.siopeia, and prolonging it an equal distance.

The Great Square is a stellar landmark. Three of the corners of the square are marked by stars in Pegasus; the fourth, and northeastern, corner is marked by the star Alpheratz in Andromeda. Each side of the square is about 18 long.

The horse is generally seen upside down, with his fore feet projected up into the sky. Only the head, neck, and fore feet are represented.

The star Enif marks the nose.

p is an interesting double, easily seen in an opera-gla.s.s. All the stars of the Square are approaching us at an inconceivable speed.

The position of the asterism Equus or Equuleus, the Little Horse, or Horse's Head, is shown in the diagram.

Delphinus, the water jar of Aquarius, and the circlet in the Western Fish, are all in the vicinity of Pegasus, and indicated in the diagram.

The winged horse is found on coins of Corinth 500 to 430 B.C. The Greeks called this constellation ?pp?s.

Pegasus seems to have been regarded in Phnicia and Egypt as the sky emblem of a ship.

Within the area of the Square Argelander counted thirty naked-eye stars.

Note a fine pair in Equuleus just west of the star Enif in Pegasus.

The position of the equinoctial colure is defined by a line connecting Polaris, Ca.s.siopei, a Andromed, and ? Pegasi.

[Ill.u.s.tration: PEGASUS]

ANDROMEDA (an-drom-e-d)--THE CHAINED LADY.

LOCATION.--The star a Alpheratz is at the northeastern corner of the great square of Pegasus, one of the stellar landmarks.

Running east from a, at almost equal distances, are four other stars, two of which are of the second magnitude. The most easterly one is Persei, known as Algol, the famous variable. Lines connecting the stars ? Andromed, Algol, and a Persei form a right-angled triangle.

The right angle is marked by Algol.

The chief object of interest in this constellation is the great nebula, the first to be discovered. It can be seen by the naked eye and it is a fine sight in an opera-gla.s.s. Its location is indicated in the diagram.

The star ? is the radiant point of the Bielid meteors, looked for in November. It is a colored double visible in a 3" gla.s.s.

The great nebula has been called the "Queen of the Nebul." It is said to have been known as far back as A.D. 905, and it was described 986 A.D. as the "Little Cloud."

Andromeda is very favorable for observation in September, low in the eastern sky.

Note the characteristic "Y" shaped asterism known as Gloria Frederika or Frederik's Glory. It lies about at the apex of a nearly isosceles triangle of which a line connecting Alpheratz and Pegasi is the base. A line drawn from d to a Ca.s.siopei and prolonged a little over twice its length points it out.

[Ill.u.s.tration: ANDROMEDA]

PERSEUS (per-sus)--THE CHAMPION. (Face Northeast.)

LOCATION.--a Persei lies on a line drawn from to ? Andromed, and is about 9 from the latter. The most striking feature in Perseus is the so-called "segment of Perseus," a curve of stars beginning about 12 below Ca.s.siopeia, and curving toward Ursa Major. Note the famous variable Algol the Demon star. It represents the Medusa's head which Perseus holds in his hand. It varies from the second to the fourth magnitude in about three and one-half hours, and back again in the same time, after which it remains steadily brilliant for two and three-quarters days, when the same change recurs. Algenib and Algol form with ? Andromed, a right-angled triangle.

Note a dull red star near Algol, and a pretty pair just above Algenib.

An opera-gla.s.s reveals much that is worthy of observation in this region of the sky. It has been said of the cl.u.s.ters between Ca.s.siopeia and Perseus that they form the most striking sidereal spectacle in the northern heavens. They are visible to the naked eye. Algenib never sets in the lat.i.tude of New York, just touching the horizon at its lower culmination. It is estimated that Algol is a little over a million miles in diameter, ? has three faint stars on one side nearly in a line, and one on the other--a miniature representation of Jupiter and his satellites.

Algol, when on the meridian of New York City, is only one tenth of a degree from the zenith point. This remarkable variable has a dark companion star revolving near it obscuring its light in part from us at stated intervals. By means of the spectroscope the speed diameter and ma.s.s of this invisible star has been reckoned.

[Ill.u.s.tration: PERSEUS]

PISCES (pisez)--THE FISHES. (Face Southeast.)

LOCATION.--This constellation is represented by two fishes each with a ribbon tied to its tail. One, the Northern Fish, lies just below Andromed,--the other, represented by the circlet, is just below Pegasus. The ribbons, represented by streams of faint stars, from a "V" with elongated sides, and terminate in the star Al Rischa, The Knot.

Below ?, and to the east of ? the spot marked (*) is the place which the sun occupies at the time of the equinox. It is one of the two crossing places of the equinoctial, or equator, of the heavens, and the ecliptic, or sun's path.

Below Pisces is Cetus, the Whale.

Pisces is thought to have taken its name from its coincidence with the sun during the rainy season.

Three distinct conjunctions of Jupiter and Saturn took place in this constellation in the year 747 of Rome.

Pisces was considered the national constellation of the Jews, as well as a tribal symbol.

In 1881, Jupiter, Saturn, and Venus were grouped together in Pisces.

The Circlet is a very striking group forming a pentagon. The gla.s.s reveals two faint stars in addition, making the figure seven-sided or elliptical in form.

As to the number of the stars as cla.s.sified according to their magnitude, that is their brightness, it may be mentioned that there are approximately 20 stars of the first magnitude, 65 of the second, 300 of the third, and 450 of the fourth. We cannot see stars fainter than the sixth magnitude with the naked eye.