Stars and the Constellations

A constellation is an area on the sky. Somewhat as the United States is divided into forty-eight states with irregular boundaries, varying greatly in shape, size, and importance, so the whole expanse of the sky is divided into constellations of varied shape, size, and importance; eighty -eight are now commonly recognized.

The brighter and fainter stars may be compared to the larger and smaller towns of a state. All heavenly bodies the sun, moon, planets, comets, and so forth, as well as the stars always lie in one or another of these eighty-eight constellations. The constellations are of little importance except for objects visible to the naked eye. The general region included in a constella tion is usually recognized by an association or a group ing of the brighter stars within it. These groups of brighter stars are also spoken of as constellations, and this is the sense in which the word is often used in what follows. " Primitive peoples, for unknown reasons, associated certain groups of stars with various living things and, in a few cases, with inanimate objects and gave names accordingly to these groups and made constellations of them. In only a few cases, does the name help in any way in locating the constellation, any more than the name of a state helps in locating the state. These ancient constellations did not fill the whole sky, so others have been added. Indeed, many other con stellations and changes have been proposed from time to time and accepted by some but not by others, and thus, some confusion exists as to names and boundaries, but the differences in present usage are neither great nor important, and the International Astronomical Union has taken steps to remove them. A much better system of constellations might have been devised, but it is now almost impossible to change greatly a system which has been in use so long. Of the eighty-eight constellations forty-eight have come down to us from ancient times and were known to Ptolemy, 150 A.D., from whom our information with respect to them is chiefly derived. A considerable number of the new ones were formed to include the stars which were too far south to be seen by those who made the ancient constellations. There are many interesting myths connected with the latter.

Greek and Latin Constellations

The names of the constellations are given in the Greek and Latin language.  English equivalents are used by some, but the Greek / Latin names are better, because they are used over the whole world and in all important astronomical literature.

It is only from places along the equator that all of the stars can be seen.  In latitude 40 degrees eight ninths of the sky can be seen but at the poles only half of it.  Some of the constellations are small in area and have few bright stars in them and are, therefore, less important than others.  Ursa Major, Centaurus, Hercules, and Virgo are very large constellations, and Sagitta, Equuleus, Scutum, and Crux are very small ones.

The boundaries of the constellations are marked on the detail charts.  It must be understood that these boundaries are entirely artificial.  There is nothing in the sky which can be compared even to the rivers and mountain ranges which, in some cases, form natural boundaries of states.  There is no relationship between the stars of the same constellation other than that of direction.  The stars within it differ enormously in their distances from us, in their brightness, both real and apparent, in their size, and all other characteristics.