For anyone who enjoys looking up at the night sky, the constellations are an incredibly accessible place to begin. You don’t need any sophisticated equipment to pick them out, and they inspire the imagination with their exotic shapes and exciting legends.
Today, we have a standardized set of 88 constellations, agreed upon by astronomers worldwide. When people first began to discern figures in the random shapes in the sky, however, it was a free-for-all. Different sky watchers each had their own interpretations, some of which became the de facto constellations in their culture, nation, or region. Constellations in Greece were not necessarily the same as those in Babylon, China, or anywhere else.
That all changed when astronomers began cataloging the night sky, putting their own interpretations, or those popularly accepted in their own corners of the world, down on paper for the generations. One such astronomer was the Greek-writing, Egyptian-born, Roman citizen Claudius Ptolemaeus, or Ptolemy for short.
One of the most influential astronomers and geographers of his time, Ptolemy was born in 90 AD and lived most of his life in Alexandria, Egypt. His major work, The Almagest (Arabic for The Greatest Compilation), was 13 volumes long and cataloged not only the 44 most commonly recognized constellations in his day, but also attempted to ascribe some order to the apparent movements of the Sun, Moon, planets, and stars. His “Handy Tables” tabulated all the data needed by astronomers who came after him to calculate the future positions of all of these heavenly bodies, as well as eclipses of the Sun and Moon. In this way, The Almagest was a kind of forebear to modern almanacs, such as the Farmers’ Almanac.
Though Ptolemy’s geocentric (Earth-centered) view of the universe was eventually discredited by Copernicus during the European renaissance, The Almagest was the most respected treatise on astronomy for more than 1,400 years.