Dernière mise à jour : 29 août 2025

Constellations

Imaginary Figures in the Sky

A constellation is a group of stars in the celestial sphere whose arrangement suggests an imaginary shape, a notable asterism formed by the brightest stars. Although these stars are in reality extremely distant from one another, they appear from Earth as coherent figures, without any inherent distance, drawn on the celestial sphere.

A Cultural and Astronomical Heritage

Western constellations are divided into two major zones: the northern sky, observed from the Mediterranean regions by astronomers in Antiquity, and the southern sky, named later by European explorers and scholars after the 15th century. In theory, an observer can distinguish with the naked eye approximately 3,800 stars, some of which form these traditional figures.

A Standardized Celestial Cartography

Today, the International Astronomical Union (IAU) officially divides the sky into 88 constellations with precise boundaries, ensuring that every point on the celestial sphere belongs to one of them. This modern organization is based on Earth's rotation, which continuously divides the celestial vault into two visible hemispheres depending on the observer's position.

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