Home >> Encyclopedia Americana, Volume 7 >> Connective Tissue to Cooke >> Constellations

Constellations

stars, names, southern, star, earliest, maps and letters

CONSTELLATIONS (Lat. con, (to gether," stella, ustar))). From the earliest times men have formed certain groups of bright stars into constellations. Thus the names of the 12 zodiacal constellations are prehistoric. The same is true of many of those clustering about the north pole of the heavens. Quite a number bear the names of members of .the Argonautic expedition, or of persons who were in some way connected with it, which deter mines the age of their formation approximately. The earliest description of the constellations of which we have any record is by Eudoxus, v:ho lived about 360 ac. This work is lost, but a poetic paraphrase of it by Aratus, who lived about 100 years later, is still extant. This work mentions 45 constellations. The earliest star catalogue which has survived to modern times is the (Syntaxis), that is, (Compenditun.) This is usually known as the (Almagest,) which means °The Greatest," of Ptokmy. His ob servations were made between 121 and 151 A.n. The catalogue contains 1,028 stars divided among 48 constellations. This completes the ancient classification, and no permanent addi tions were made to it until 1602, when one con stellation was added by Tycho Brahe. The next year appeared Bayer's (Uranometria,) a series of star-maps containing 1,709 stars and 12 new southern constellations. These maps were decorated by a series of drawings made by Diner, whose outlines have until recently served to ornament the constellations as rep resented on certain maps and stellar globes. These were the first star-maps published, al though stellar globes were introduced in the middle of the previous century by Mercator.

Before Bayer's time it was customary to describe the position of a star by its location in the animal or figure represented by the con stellation. Thus Aldebaran was the bright star in the eye of the bull. From this it would appear that the ancients had manuscript maps with figures drawn upon them, but none of these maps have come down to our time. Bayer introduced the important innovation of letter ing the various stars with the letters of the Greek and Roman alphabets, a separate set of letters being used for each constellation, thereby greatly simplifying the designation of any par ticular star. Strangely enough he did not letter

his 12 new southern constellations, so that these stars still had to be designated by the cutnbrous methods of the ancients. In Flaw steed's catalogue, issued early in the 18th cen tury, the stars are numbered in the order of thetr right ascension, and both letters and num bers are still in general use. From the earliest times some of the brightest stars have received special names, such as Sirius, Arcturus, etc, Although these are still in common use, there is a tendency among astronomers to substitute Bayer's nomenclature in their place.

Following. Bayer a number of new constel lations were introduced by various astronomers, notably Hevelius, Lacaille and Royer. Many constellations were proposed which have failed to meet with universal acceptance, and the tuna ber which is now generally adopted by astron omers is 67. There is no definite agreement as to their exact outlines. Indeed, such an agree ment would be impossible unless the boundaries followed definite circles of the celestial sphere. All stars brighter than the 9.5 magnitude are now designated by their numbers m certain large modern catalogues. Fainter stars are lo cated by their right ascension and declination at certain dates. These quantities correspond to terrestrial longitude and latitude.

The shapes of the constellations are entirely matters of accident, and in only a few instances are the brighter stars contained in them ar ranged in such a manner as to bear any resem blance to the object for which the constellation is named. The exceptions to this rule are the Scorpion, the Southern Cross, the Northern and Southern Crowns and the Southern Triangle. On the other hand, certain characteristic forms are obvious in the heavens which bear no rela tion to the name of the constellation in which they occur. The Great Dipper in Ursa Major, known in England as Charles' Wain (or Wagon), the Y in Bootes, the Sicide in Leo and- the Cross in Cygnus are well-lmown exam ples. Good modern star-atlases have been published by Schurig and by Upton. For the most complete work in English on the early history of the constellations and the origin of the names of the stars, consult Allen, R. H., (Star Names and Their Meaniiit:rs) (1899).