The Cygnus Wall of Star Formation
The Cygnus Wall in Hydrogen-Alpha: Taken under Michigan Skies, July 2022. In the 2nd century CE, Claudius Ptolemaeus (Ptolemy) wrote the Almagest; a mathematical and astronomical treatise on the apparent motions of the stars and the planets. This influential text was leveraged for the next 1,200 years to support the geocentric solar system (earth-centered) until the the early Renaissance when the helio-centric (sun-centereed) model was developed by Nicolaus Copernicus. In the Almagest, Ptolemy had divided the night sky into 48 constellations; Cygnus being one of them. The constellation Cygnus, being Greek for Swan, earned its name because the brighter stars in this area of sky seem to resemble that of a bird in flight. What people in Ptolemy's time could not know, was the massive amount of nebulous activity that exists within this region of sky. From the massive regions of hydrogen that spread far around the star Sadr, to the North America Nebula spread around Deneb and to the left