Star catalogue

A star catalogue (Commonwealth English) or star catalog (American English), is an astronomical catalogue that lists stars. In astronomy, many stars are referred to simply by catalogue numbers. There are a great many different star catalogues which have been produced for different purposes over the years, and this article covers only some of the more frequently quoted ones. Star catalogues were compiled by many different ancient people, including the Babylonians, Greeks, Chinese, Persians, and Arabs. They were sometimes accompanied by a star chart for illustration. Most modern catalogues are available in electronic format and can be freely downloaded from space agencies data centres. A star catalogue (Commonwealth English) or star catalog (American English), is an astronomical catalogue that lists stars. In astronomy, many stars are referred to simply by catalogue numbers. There are a great many different star catalogues which have been produced for different purposes over the years, and this article covers only some of the more frequently quoted ones. Star catalogues were compiled by many different ancient people, including the Babylonians, Greeks, Chinese, Persians, and Arabs. They were sometimes accompanied by a star chart for illustration. Most modern catalogues are available in electronic format and can be freely downloaded from space agencies data centres. Completeness and accuracy is described by the weakest apparent magnitude V (largest number) and the accuracy of the positions. From their existing records, it is known that the ancient Egyptians recorded the names of only a few identifiable constellations and a list of thirty-six decans that were used as a star clock. The Egyptians called the circumpolar star 'the star that cannot perish' and, although they made no known formal star catalogues, they nonetheless created extensive star charts of the night sky which adorn the coffins and ceilings of tomb chambers. Although the ancient Sumerians were the first to record the names of constellations on clay tablets, the earliest known star catalogues were compiled by the ancient Babylonians of Mesopotamia in the late 2nd millennium BC, during the Kassite Period (c. 1531 BC to c. 1155 BC). They are better known by their Assyrian-era name 'Three Stars Each'. These star catalogues, written on clay tablets, listed thirty-six stars: twelve for 'Anu' along the celestial equator, twelve for 'Ea' south of that, and twelve for 'Enlil' to the north. The Mul.Apin lists, dated to sometime before the Neo-Babylonian Empire (626–539 BC), are direct textual descendants of the 'Three Stars Each' lists and their constellation patterns show similarities to those of later Greek civilization. In Ancient Greece, the astronomer and mathematician Eudoxus laid down a full set of the classical constellations around 370 BC. His catalogue Phaenomena, rewritten by Aratus of Soli between 275 and 250 BC as a didactic poem, became one of the most consulted astronomical texts in antiquity and beyond. It contains descriptions of the positions of the stars, the shapes of the constellations and provided information on their relative times of rising and setting. Approximately in the 3rd century BC, the Greek astronomers Timocharis of Alexandria and Aristillus created another star catalogue. Hipparchus (c. 190 – c. 120 BC) completed his star catalogue in 129 BC, which he compared to Timocharis' and discovered that the longitude of the stars had changed over time. This led him to determine the first value of the precession of the equinoxes. In the 2nd century, Ptolemy (c. 90 – c. 186 AD) of Roman Egypt published a star catalogue as part of his Almagest, which listed 1,022 stars visible from Alexandria. Ptolemy's catalogue was based almost entirely on an earlier one by Hipparchus. It remained the standard star catalogue in the Western and Arab worlds for over eight centuries. The Islamic astronomer al-Sufi updated it in 964, and the star positions were redetermined by Ulugh Beg in 1437, but it was not fully superseded until the appearance of the thousand-star catalogue of Tycho Brahe in 1598. Although the ancient Vedas of India specified how the ecliptic was to be divided into twenty-eight nakshatra, Indian constellation patterns were ultimately borrowed from Greek ones sometime after Alexander's conquests in Asia in the 4th century BC. The earliest known inscriptions for Chinese star names were written on oracle bones and date to the Shang Dynasty (c. 1600 – c. 1050 BC). Sources dating from the Zhou Dynasty (c. 1050 – 256 BC) which provide star names include the Zuo Zhuan, the Shi Jing, and the 'Canon of Yao' (堯典) in the Book of Documents. The Lüshi Chunqiu written by the Qin statesman Lü Buwei (d. 235 BC) provides most of the names for the twenty-eight mansions (i.e. asterisms across the ecliptic belt of the celestial sphere used for constructing the calendar). An earlier lacquerware chest found in the Tomb of Marquis Yi of Zeng (interred in 433 BC) contains a complete list of the names of the twenty-eight mansions. Star catalogues are traditionally attributed to Shi Shen and Gan De, two rather obscure Chinese astronomers who may have been active in the 4th century BC of the Warring States period (403–221 BC). The Shi Shen astronomy (石申天文, Shi Shen tienwen) is attributed to Shi Shen, and the Astronomic star observation (天文星占, Tianwen xingzhan) to Gan De. It was not until the Han Dynasty (202 BC – 220 AD) that astronomers started to observe and record names for all the stars that were apparent (to the naked eye) in the night sky, not just those around the ecliptic. A star catalogue is featured in one of the chapters of the late 2nd-century-BC history work Records of the Grand Historian by Sima Qian (145–86 BC) and contains the 'schools' of Shi Shen and Gan De's work (i.e. the different constellations they allegedly focused on for astrological purposes). Sima's catalogue—the Book of Celestial Offices (天官書 Tianguan shu)—includes some 90 constellations, the stars therein named after temples, ideas in philosophy, locations such as markets and shops, and different people such as farmers and soldiers. For his Spiritual Constitution of the Universe (靈憲, Ling Xian) of 120 AD, the astronomer Zhang Heng (78–139 AD) compiled a star catalogue comprising 124 constellations. Chinese constellation names were later adopted by the Koreans and Japanese.