<P> A constellation is a group of stars that are considered to form imaginary outlines or meaningful patterns on the celestial sphere, typically representing animals, mythological people or gods, mythological creatures, or manufactured devices . The 88 modern constellations are defined regions of the sky together covering the entire celestial sphere . </P> <P> Origins for the earliest constellations likely goes back to prehistory, whose now unknown creators collectively used them to related important stories of either their beliefs, experiences, creation or mythology . As such, different cultures and countries often adopted their own set of constellations outlines, some that persisted into the early 20th Century . Adoption of numerous constellations have significantly changed throughout the centuries . Many have varied in size or shape, while some became popular then dropped into obscurity . Others were traditionally used only by various cultures or single nations . </P> <P> The Western - traditional constellations are the forty - eight Greek classical patterns, as stated in both Aratus' work Phenomena or Ptolemy's Almagest--though their existence probably predates these constellation names by several centuries . Newer constellations in the far southern sky were added much later during the 15th to mid-18th century, when European explorers began travelling to the southern hemisphere . Twelve important constellations are assigned to the zodiac, where the Sun, Moon, and planets all follow the ecliptic . The origins of the zodiac probably date back into prehistory, whose astrological divisions became prominent c. 400 BC within Babylonian or Chaldean astronomy . </P> <P> In 1928, the International Astronomical Union (IAU) ratified and recognized 88 modern constellations, with contiguous boundaries defined by right ascension and declination . Therefore, any given point in a celestial coordinate system lies in one of the modern constellations . Some astronomical naming systems give the constellation where a given celestial object is found along with a designation in order to convey an approximate idea of its location in the sky . e.g. The Flamsteed designation for bright stars consists of a number and the genitive form of the constellation name . </P>

There are 80 separate constellations that make up the celestial sphere