How were constellations decided?

Constellations were decided through a combination of ancient observation and cultural significance, with early civilizations mapping the night sky based on patterns they saw in the stars. Different cultures often assigned their own meanings and stories to these patterns, leading to variations in constellations across different regions. The modern system was largely standardized by the International Astronomical Union in the 20th century, which officially recognized 88 constellations based on historical traditions and astronomical criteria.