what are constellations?
In English, we call groups of stars constellations. Constellations aren’t just any group of stars though; a constellation is a group of stars that fit together in a pattern.
The images above show three of the most well-known constellations: Ursa Major (or the Great Bear), Orion (the Great Hunter), and Crux (or the Southern Cross).
Where do they come from?
The word constellation comes from Latin, which was the language people spoke in ancient Rome. Many of the words astronomers use to name stars and constellations come from Latin as well. A Roman astronomer named Ptolemy studied and documented the first official constellations, although it’s likely that much of what he knew about the constellations he learned from studying the work of earlier astronomers from Middle Eastern civilizations.
Before constellations were standardized, everyone recognized different star patterns and told different stories about them. Some star patterns were more easily seen than others, since some stars are brighter than others. Other star patterns were more visible in some parts of the world than others. These differences were fine when stargazing was a recreational activity. But for star patterns to be studied seriously, there had to be consistency. The star patterns had to be given official names and shapes that everyone could recognize, wherever they were in the world.
Ptolemy documented 48 constellations, but in the seventeenth and eighteenth centuries, European astronomers added another 40. In the 1920s, the International Astronomical Union defined these 88 constellations for modern times. Standardization was an important step in making astronomy a science. Standardization meant that if an astronomer noticed something new about a part of the sky, he could easily and precisely explain to other astronomers where to look. Then they could check his findings and see if they noticed the same thing.
Constellations work as landmarks in the sky. When you can find a constellation or part of a constellation, you can follow the shape to find all of the stars in the constellation. Constellations also map the night sky. Each constellation marks a particular region of the sky that also contains a recognized star pattern. The Little Dipper star pattern, including the star Polaris, exists within the constellation Ursa Minor, or the Little Bear. The Big Dipper star pattern actually exists within a large constellation called Ursa Major, or the Great Bear.
Before constellations were standardized, everyone recognized different star patterns and told different stories about them. Some star patterns were more easily seen than others, since some stars are brighter than others. Other star patterns were more visible in some parts of the world than others. These differences were fine when stargazing was a recreational activity. But for star patterns to be studied seriously, there had to be consistency. The star patterns had to be given official names and shapes that everyone could recognize, wherever they were in the world.
Ptolemy documented 48 constellations, but in the seventeenth and eighteenth centuries, European astronomers added another 40. In the 1920s, the International Astronomical Union defined these 88 constellations for modern times. Standardization was an important step in making astronomy a science. Standardization meant that if an astronomer noticed something new about a part of the sky, he could easily and precisely explain to other astronomers where to look. Then they could check his findings and see if they noticed the same thing.
Constellations work as landmarks in the sky. When you can find a constellation or part of a constellation, you can follow the shape to find all of the stars in the constellation. Constellations also map the night sky. Each constellation marks a particular region of the sky that also contains a recognized star pattern. The Little Dipper star pattern, including the star Polaris, exists within the constellation Ursa Minor, or the Little Bear. The Big Dipper star pattern actually exists within a large constellation called Ursa Major, or the Great Bear.
The constellation Ursa Major includes the Big Dipper, the official "Great Bear" star pattern, and all of the space around the star pattern.
Together, the constellations make up a grid that covers the entire night sky. The grid cells, like the constellations themselves, come in wildly different sizes and shapes.
Together, the constellations make up a grid that covers the entire night sky. The grid cells, like the constellations themselves, come in wildly different sizes and shapes.