What Are Star Constellations?

Purpose

• The purpose of star constellations is to help astronomers map out the sky and identify certain stars.

Identification

• Some constellations, such as the big and little dippers, are easily identified due to their tell-tale shape. The constellation Orion is popular for three of its stars that are lined up perfectly in a row known as Orion's Belt.

History

• Constellations have been documented by the Sumerians, Babylonians, Ancient Egyptians and Ancient Greeks. Half of the 88 constellations recognized by the International Astronomical Union were first described by the Greeks. Twelve of these include the constellations of the Zodiac.

Fixed Stars

• Constellations may appear different now than they did to our ancestors thousands of years ago. Although they are described as 'fixed stars', stars do move, but not at a rate high enough to be visible within a person's lifetime.

Circumpolar vs. Seasonal Constellations

• Some constellations are visible all year while others only appear during specific seasons. For example, in the Northern hemisphere, the big and little dippers are can be seen year-round, but Orion is visible only in the winter.