stjärnbilderna

Stjärnbilderna, or constellations, are recognized patterns of stars in the night sky. Historically, these patterns were used by ancient civilizations for navigation, agriculture, and storytelling. The International Astronomical Union (IAU) officially recognizes 88 constellations, which divide the entire celestial sphere. Each constellation has a defined boundary, ensuring that every star in the sky belongs to a specific constellation.

These star patterns are not physically related; the stars within a constellation are often at vastly different distances from Earth. Their apparent proximity is merely a matter of perspective from our viewpoint on Earth. Many constellations are named after mythological figures, animals, or objects, reflecting the cultural significance they held for those who first observed and named them. Common examples include Ursa Major (the Great Bear), Orion (the Hunter), and Leo (the Lion).

While the stars themselves are constant, the patterns they form can appear to change over the course of a night due to the Earth's rotation, and over longer periods due to the Earth's orbit around the Sun. Different constellations are visible from different hemispheres and at different times of the year. For observers in the Northern Hemisphere, Ursa Major, Ursa Minor, and Cassiopeia are circumpolar, meaning they are visible year-round. Southern Hemisphere observers can easily spot Crux (the Southern Cross) and Centaurus. Modern astronomy uses constellations primarily as a convenient way to map and locate celestial objects.