The history of constellations Viewing southern constellations

Constellations are visible groups of stars that appear as patterns in the sky. The Southern Cross and Orion are constellations. Different cultures have different names and see different patterns in the same sets of stars. For example, Orion "The Hunter" is also known as "The Turtle" to the Thai people.

Astronomically, constellations are not real groups of stars like galaxies. Constellations do have an important role to play as guides or references in the night sky. The stars in the Southern Cross and pointers display this well; they are important as direction finders in the Southern Hemisphere. The stars themselves range in distance from Earth to Alpha Centauri at 4.3 light years to Delta Crucis at 590 light years.

Relative distances - stars

The history of constellations
From the earliest times, constellations, parts of constellations (known as asterisms), and individual stars have received names depicting meteorological phenomena or religious and mythological beliefs. Constellation names are steeped in history, with many coming from the ancient Greeks. Forty eight constellations were named in ancient times, with another 40 constellations added by European astronomers in the 17th and 18th centuries.

In the 20th century, the sky or celestial globe was divided up into 88 constellations with precise boundaries by the International Astronomical Union. By 1930, all stars had been assigned to a constellation. This aided in easier identification and positioning of stars in the sky, but says nothing about their nature or true place in space, only their direction from Earth.

Viewing southern constellations
On a clear, dark night, the southern night sky is spectacular - especially in winter, when we have the best possible view of the Milky Way.

The most well known of the Southern Hemisphere constellations is Crux Australis, better known as the Southern Cross. Its long axis is, by chance, directed to the point in the sky called the South Celestial Pole, which is exactly above the southern horizon. It is so far south that its stars were not well known by ancient Northern Hemisphere astronomers. The first references to it as having the shape of a Cross seem to come from Andrea Corsali, the Italian explorer, in 1517.

The next most well known is probably Orion, a giant hunter from Greek Mythology. The stars do indeed appear to have the shape of a man wielding a club and having a sword attached to his belt. It is the stars of the belt that make Orion easy to spot - the belt is formed by three bright stars in a nearly straight line.

The Southern Cross, Orion, and other southern constellations are shown on the star map.

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