The constellations are groups of stars we can see in the night sky. The word constellation can also mean the part of the sky in which one group of stars is seen. Astronomers, or scientists who study the stars, have divided the sky into 88 areas, or constellations. We often use Latin names for constellations. Latin was the language of the ancient Romans.

Long ago, the people of early civilizations studied the night sky. They saw groups of stars that seemed to form shapes or patterns. Finding picture-shapes in the constellations made it easier to find one group of stars among the thousands of stars in the sky. They named the star-groups after animals, gods, and characters in stories. For example, they named one constellation Leo, a Latin word meaning lion. They named another constellation Andromeda, after a heroine in an old Greek story. They also saw and named the constellations Orion, the Hunter, and Ursa Major, the Great Bear. Image to right: This map shows 7 of the 88 constellations in the sky. Credit: World Book illustration by Rob Wood

Half of the sky can be seen from the North Pole and the other half can be seen from the South Pole. The equator is an imaginary line around Earth's middle, halfway between the North and South poles. Between the 1400s and 1700s, Europeans explored the southern part of the world and named the star groups they saw there. Someone at the equator can see all the constellations during the course of a year. How to cite this article: To cite this article, World Book recommends the following format: "Constellation." The World Book Student Discovery Encyclopedia. Chicago: World Book, Inc., 2005.