The ancient Greeks were instrumental in shaping the concept of constellations as we understand them today. They began formalising the star patterns, assigning them specific names and mythological stories, many of which have persisted into modern astronomy. Eudoxus of Cnidus, an early Greek astronomer, is believed to have created a celestial globe that displayed the constellations in the 4th century BCE. The term “constellatio” was used in ancient Roman times.
Magnitudes
In the 130s BCE, Greek astronomer and inventor of geometry Hipparchus of Nicaea, made the first accurate star catalogue containing about 800 stars. He noted that different stars have different brightnesses and assigned them numbers. Hipparchus was a mathematician and the first to use quantitative and accurate models for the motion of the Sun and Moon, which survived to today. He is considered the greatest ancient astronomical observer and, by some, the greatest overall astronomer of antiquity.
The earliest known surviving pictorial representation of the complete night sky from any civilisation is the Dunhuang Star Map (featured photo) from ancient China. This map, dated to the Tang Dynasty (618–907 CE), shows over a thousand stars and the Milky Way.
1603 German-Dutch astronomer Johann Bayer created Uranometria with detailed charts of 1200 stars. Bayer introduced a system of identifying stars within each constellation using Greek and Latin letters, now known as Bayer designations. This system, where stars are labelled with a letter followed by the genitive form of their constellation’s name (for example, Alpha Centauri), is still used today for naming stars.
First stellar catalogue
When telescopes were invented in 1609, more stars were discovered. Galileo Galilei’s first telescope could magnify up to three times! He published his observations in Siderius Nuncius, but the first catalogue of stars that included telescopic observations, thus going beyond what was visible to the unaided eye, was created by Giovanni Battista Hodierna in 1654: De systemate orbis cometici, deque admirandis coeli characteribus (Of the systematics of the world of comets, and on the admirable objects of the sky).
More Stellar Catalogues
Flamsteed’s “Historia Coelestis Britannica” (1725), Messier Catalog (1781), Bode’s “Uranographia” (1801), The Bonner Durchmusterung (1852-1862), Henry Draper Catalogue (late 19th – early 20th century), John Herschel’s General Catalogue of Nebulae and Clusters of Stars” (GC) 1864 and Dreyer’s New General Catalogue of Nebulae and Clusters of Stars” (NGC) are examples of catalogues that have been developed throughout the years. The Yale Bright Star Catalogue (1982) lists 9095 stars visible to the unaided eye covering the northern and southern hemispheres, setting 6.5 as the limiting magnitude.
With so many catalogues, astronomers ended up with over a hundred constellations, some newly invented, because nothing stopped them from adding more. Not only astronomers but different cultures, over centuries, have identified various patterns in the stars. “This inconsistency posed a problem for scientific communication and research, as astronomers around the world were using different maps and names for the same regions of the sky.”(IAU),
