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| The Constellations |
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The starry sky is divided up by mankind's imagination into 88 areas called constellations. They serve as a convenient way of locating the position of objects in the sky. The stars of a constellation usually have no actual physical connection between one another. They just happen to be visible in the same general line of sight and vary greatly in distance from us and from each other.
Shapes and Sizes
Constellations come in many different shapes and sizes. The largest constellation, Hydra, the water snake, is a long and rambling figure that covers an area 19 times greater than the area of the smallest constellation, Crux, the Southern Cross. Some constellations such as Scorpius are easily recognisable patterns. Others require that the viewer drink whatever the ancients were drinking when they imagined the often strange resemblances to the star patterns.
Constellation Origins
The tradition of dividing the sky into constellations began thousands of years ago when ancient peoples assigned certain star patterns the names of their gods, heroes and fabled animals. The ancient Greeks recognised a total of 48 constellations which included the 12 constellations of the zodiac, that is, constellations which lie on an imaginary line through which the Sun passes on it's annual path around the sky.
Early celestial cartographers drew the established constellation figures as they pleased, because there was no standard shape for each one. Cartographers often invented their own constellations and omitted those invented by others. A Formal List of Constellations
This confused state persisted until 1930 when the International Astronomical Union adopted the list of 88 constellations that we accept today. In doing so, they clearly defined the boundaries between the constellations to eliminate confusion as to the correct constellation in which a star could be found.
The number of 88 constellations has no significance. After all the decision making there just happened to be that number of constellations. Rather like the political map of the world, the subdivision of the sky is an accident of history.
Southern Hemisphere Constellations
The constellations visible from the northern hemisphere were invented by the ancient civilisations in the northern countries thousands of years ago. They mainly commemorated mythological beings and creatures. It was only when those civilisations had advanced sufficiently that they were able to venture into the southern hemisphere in the their sailing ships. They saw stars never previously seen from the northern hemisphere and because they navigated by the stars, they soon grouped the patterns they saw into constellations named after items familiar to them such as the clock named Horologium or the microscope named Microscopium. |
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