A constellation is a group of stars that seem to form the shape of an animal, person, or object when viewed from the earth. The term comes from the Latin word stella, which means “star.”
But the stars in a constellation only appear to form a shape, and may not even belong to the same group of stars or even the same galaxies. For instance, two stars that appear to be close together in the sky may actually be billions of miles apart, and may not even be stars themselves, but entire galaxies!
The people of ancient Mesopotamia were the first to outline the patterns that stars form in the sky, and the first to name them. The Greeks later took over these constellations, but changed their names. Then the Romans did the same. We still use the Latin names for most of the constellations.
Ancient astronomers named 48 constellations, but we now list 88. Some constellations are formed by just a few stars, while others consist of dozens. But every star visible in the sky lies within one of the constellations.
For example, the stars that form the Big Dipper and the Little Dipper, which are parts of constellations, and not constellations themselves, are easy to spot, but others are very hard to find.
The constellations in the sky look different when viewed from the Northern Hemisphere than they do when viewed from the Southern Hemisphere!