There are 88 constellations recognized by the International Astronomical Union (IAU) that cover the entire celestial sphere.

These constellations are divided into two categories: northern constellations and southern constellations. The majority of the constellations, 48 in fact, are located in the northern hemisphere and are therefore visible to observers in the northern hemisphere during their respective seasons. Conversely, the remaining 40 constellations are located in the southern hemisphere and are visible during their respective seasons to observers in the southern hemisphere.

Each constellation is defined by a specific area of the sky that is designated by the IAU. The areas of the sky that these star patterns cover are known as "zones" and vary in size from one constellation to another. The smallest constellation, Crux (the Southern Cross), covers an area of just 68 square degrees, while the largest constellation, Hydra (the Sea Serpent), covers an area of 1,303 square degrees.

The constellations were originally created by ancient civilizations who looked to the night sky for guidance and meaning. Many of them were initially used as navigational aids for sailors and adventurers traveling across the globe. Over time, various cultures added their own mythologies and stories to these constellations, mapping out specific star patterns and assigning them intricate names and meanings.

Today, the constellations are still used as navigational aids by astronomers and stargazers alike. They serve as a way to locate specific points in the night sky and to identify different celestial objects, such as stars, planets, and galaxies. They also provide a rich history and culture that has been passed down from generation to generation, connecting us to our past and to the universe beyond.