There are 88 constellations in the modern list, which were recognized in 1928 by the International Astronomical Union (IAU). The Chinese developed their own system of naming constellations, which is very different from the constellations developed by the Greeks and adopted by the Western world. The Chinese divided the sky into 31 regions, which is less than half of the 88 constellations recognized by modern astronomy. Because stars grow brighter and dim over hundreds of years, astronomers stopped defining a constellation as merely the pattern of the stars. Instead, they started defining a constellation as a region of the sky with defined borders.
Many of the 88 constellations were discovered over a thousand years ago. The Greek astronomer Claudius Ptolemy catalogued 48 of the IAU’s 88 constellations in his book Almagest. Some of these constellations include Lupus, Sagitta, and Cetus. In addition to other constellations, the 12 zodiac constellations also appeared in Ptolemy’s book.
As evidenced by the zodiac signs, the ancient Greeks named the constellations after figures in their legends and mythology. This followed in their tradition of naming celestial objects after figures from legends because they named the planets after their gods. Some in the 1500’s but mostly in the 1600’s and 1700’s, European astronomers began discovering new constellations; some of them they split from older constellations. These discoveries were in part due to better telescopes and other astronomical instruments. Unlike the Greeks though, they did not name the new constellations after mythological figures. Instead, many of the Europeans named them after scientific instruments.
Nicolas Louis de Lacaille was an astronomer in the 1700’s who named 15 of 88 constellations, many of them after scientific instruments. Johannes Hevelius also named a number of constellations after scientific instruments, especially after most of his astronomical instruments were destroyed in a fire. Some of the constellations named after instruments include Antlia which means the Air Pump and Octans which is the Mariner’s Octant. Peter Plancius was an astronomer who named some other constellations. An explorer as well as an astronomer, he named them after exotic locations and species of animals. Some examples include Camelopardalis (the Giraffe) and Columba (Noah’s Dove). A number of other astronomers also discovered constellations during that time period.
Watching constellations is popular pastime for many people. Some of the constellations are very well known, including the zodiac constellations, and a number of constellations can even be seen without the use of a telescope.
Astronomy Cast has an episode on constellations.