The Constellations

The history of constellations goes back millennia. Our modern constellations likely evolved from sky images from Mesopotamia by way of ancient Greece. The Greek mathematician and astronomer, Eudoxus of Cnidus (c.390BC-c.340BC), studied astronomy in Egypt and subsequently wrote his description of the sky in his works the Enoptron (the Mirror) and the Phaenomena (Appearances). Although these works are lost, the descriptions are preserved in a poem written by the Greek poet, Aratus of Soli (c.315BC-c.245BC) while at the court of Antigonus II in Macedonia. The Phaenomena of Aratus provides one of the earliest texts still available that describe the 48 ancient Greek constellations.

Subsequent additions to these constellations were made by mapmakers and astronomers during the 17th and 18th centuries as exploration of the southern hemisphere and the use of telescopes increased the range of known stars. In this period, the star charts of Johann Bayer (1572-1625), Johannes Hevelius (1611-1687), and Nicolas Louis de Lacaille (1713-1762) added almost 40 new constellations.

In 1930, the International Astronomical Union (IAU), aka Union Astronomique Internationale, officially divided the entire sky into new constellations, publishing precise boundaries. Modern usage eliminates their constellation, Argo (Arg), replacing it with the component constellations Carina (Car), Puppis (Pup), and Vela (Vel), so that we now have 88 modern constellations.

Of course, this tradition is independent of other traditions such as the Chinese, Inuit, Pacific Islander, Indian, Native American, etc., who created very different patterns in the sky. Instead of the term 'constellation', these groupings are usually referred to as asterisms, differentiating them from official constellations.