Orion constellation from Bayer's Uranometria, 1661 edition. Orion is a prominent constellation located on the celestial equator and visible throughout the world. It is one of the most conspicuous and most recognizable constellations in the night sky. Orion was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations defined by the International Astronomical Union. The stars of Orion were associated with Osiris, the sun god of rebirth and afterlife, by the ancient Egyptians. In artistic renderings, the surrounding constellations are sometimes related to Orion: he is sometimes depicted to have a lion's hide in his hand. Johann Bayer's star atlas Uranometria Omnium Asterismorum, was first published in 1603. It was the first atlas to cover the entire celestial sphere. The Uranometria introduced a new system of star designation which has become known as the Bayer designation. His atlas added 12 new constellations to fill in the far south of the night sky, which was unknown to ancient Greece and Rome.