Most of the stars in a constellation have no real connection with each other at all. They may all lie at vastly different distances from Earth, and simply form a pattern by chance. The main stars in each constellation are labeled with a letter of the Greek alphabet, the brightest star usually being termed alpha.

The brightness of a star is called its magnitude. Stars have different brightness for two reasons. First, stars radiate different amounts of light; more energetic stars are the brightest . Second, stars lie at vastly differing distances from the Earth. A small star that is close to the Earth can appear brighter than a large star that is far away from the Earth.

See if you can find the 88 constellations and then read more about the Zodiac and how astronomy and astrology are different.

Constellations can help make the heavens come alike for the observer. Each image in the sky helps to chart an area so it is easy to identify. A constellation refers to an entire sector, but there are many patterns that can be identified. An asterism is a pattern of stars that does not form the main or full pattern of an "official" constellation. For example, in the northern hemisphere the Big Dipper is only an asterism of the official Ursa Major (the Great Bear). Ursa Minor, the Little Bear constellation is visible in the northern hemisphere all year long. Polaris, the North Star can be found at the end of the asterism, the Little Dipper. Ursa Minor was created in the 6^th century B.C. as a navigational aid for sailors. Can you find the Little Dipper in the figure to the right?