What are Astronomical Constellations?
Astronomical constellations are officially defined regions of the sky by the International Astronomical Union (IAU). There are 88 constellations that cover the entire celestial sphere, including 12 zodiacal constellations.
Each constellation has a fascinating history, usually derived from Greek, Roman, or other ancient cultures' mythology. Constellations have been used for millennia for navigation, agriculture, and as a celestial calendar.
The 88 Modern Constellations
The current list of 88 constellations was established by the IAU in 1922 and their boundaries were defined in 1930. They include the 48 constellations described by Ptolemy in the 2nd century AD, plus 40 constellations added later, mainly from the southern hemisphere.