Due to Roman and European transmission, each constellation has a Latin name. Constellations in the far southern sky were added from the 15th century until the mid-18th century when European explorers began traveling to the Southern Hemisphere. The formation of constellations was the subject of extensive mythology, most notably in the Metamorphoses of the Latin poet Ovid. The traditional 48 constellations, consisting of the Zodiac and 36 more (now 38, following the division of Argo Navis into three constellations) are listed by Ptolemy, a Greco-Roman astronomer from Alexandria, Egypt, in his Almagest. Constellations appear in Western culture via Greece and are mentioned in the works of Hesiod, Eudoxus and Aratus. 400 BC in Babylonian or Chaldean astronomy. The origins of the zodiac remain historically uncertain its astrological divisions became prominent c. Twelve (or thirteen) ancient constellations belong to the zodiac (straddling the ecliptic, which the Sun, Moon, and planets all traverse). Naming constellations also helped astronomers and navigators identify stars more easily. Some were limited to a single culture or nation. Some became popular, only to drop into obscurity. The recognition of constellations has changed significantly over time. Different cultures and countries invented their own constellations, some of which lasted into the early 20th century before today's constellations were internationally recognized. People used them to relate stories of their beliefs, experiences, creation, or mythology. The origins of the earliest constellations likely go back to prehistory. Bottom: Contemporary map of Orion from the IAU (left) and photograph of the night sky with drawn lines (right)Ī constellation is an area on the celestial sphere in which a group of visible stars forms a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object.Top: Baroque drawing of Orion from Johannes Hevelius ' star atlas Firmamentum Sobiescianum, showing the stars as they would appear to an observer looking down upon the imaginary celestial sphere from the outside (left) and illustration from the medieval Persian astronomical text Book of Fixed Stars (right).

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