The international astronomical union defines a constellation by its

Answer 1

area on the celestial sphere and its boundaries. A constellation is essentially a specific region of the sky that contains a group of stars. The boundaries of a constellation are determined by the IAU, and they are used to organize the night sky into recognizable patterns. This allows astronomers and others to easily locate and identify specific celestial objects, such as stars, planets, and deep sky objects, within a particular constellation.