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Constellations

Every culture known to history and anthropology has seen in the heavens distinctive patterns, called constellations, formed by the stars. Constellations are usually comprised of bright stars which appear close to each other. Most of the constellations visible from the northern hemisphere which are "officially" recognized are of ancient Greek derivation. Ancient poetry indicates that the Greek system of constellations was well known by 2700 B.C. and that it probably originated around 3000 B.C. It is important to recognize, however, the cultural bias introduced in our vision of the sky by the selection of these constellations, while those of western civilization are usually comprised of the brighter stars, oriental cultures (the ancient Chinese, for example) formed intricate patterns from some of the faintest stars, creating hundreds of constellations where the West saw only a few. A few constellations, such as Orion, the hunter, and Ursa Major, the Great Bear, represent the same image to widely separated cultures.

Because of the rotation of the Earth and it's orbit around the Sun, it is convenient to divide the constellations into two groups. Those which never rise nor set are called circumpolar constellations. All the rest are divided into ``seasonal'' constellations. As the Earth revolves about the Sun, the Sun appears to move through the constellations. Therefore, different constellations will be visible in our night sky at different times of the year. Which constellations will be circumpolar and which seasonal depends on your latitude. From the North or South Poles, there are no seasonal constellations; all are circumpolar. From the Equator, no constellations are circumpolar. Click here to learn about the constellations which are visible in the Spring for people who live North of the Equator and in the Fall for people who live South of the Equator.

An Introduction to the Night Sky
Northern Spring and Southern Fall Constellations

The Constellation Orion
Click on image for full size (55K JPEG)
NASA



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