Constellatio

Constellatio is the Latin term for a group of stars that forms a recognizable pattern in the sky, typically translated into English as constellation. In classical Latin, the word denoted a configuration of stars used for navigation, calendars, or mythological storytelling. The modern English word constellation derives from this Latin term.

In the history of astronomy, constellatio referred to both the observed pattern and the region of the celestial sphere assigned to that pattern by scholars and, later, by organizations such as the International Astronomical Union, which formalized 88 official constellations with defined celestial boundaries.

There is a distinction between a constellation and an asterism, the latter being a recognizable pattern of stars that does not have official boundaries or name; examples include the Big Dipper, which is part of Ursa Major, and the Summer Triangle.

Cultural significance: Constellations have figures in many traditions, with myths, navigation, and calendars; the same star patterns may be identified differently across cultures and historical periods.

In modern usage, constellatio is largely historical or linguistic; scientists refer to constellations by their IAU names in Latin or English. The concept remains foundational in how humans organize and describe the night sky, even as observational and computational methods have evolved.