Modern Western (IAU)

The eighty-eight constellations with boundaries formally fixed by the International Astronomical Union in the 1920s, the standard modern astronomy now uses worldwide. The IAU set reorganised and extended the classical forty-eight constellations of Ptolemy's Almagest into fixed regions of sky with straight boundary lines, so that every point in the sky belongs to exactly one constellation, a scientific convention rather than a mythological figure traced between stars.