|
Triangulum is a small constellation in the northern sky. Its name is Latin for "triangle", derived from its three brightest stars, which form a long and narrow triangle. Known to the ancient Babylonians and Greeks, Triangulum was one of the 48 constellations listed by the 2nd century astronomer Ptolemy. The celestial cartographers Johann Bayer and John Flamsteed catalogued the constellation's stars, giving six of them Bayer designations. The white stars Beta and Gamma Trianguli, of apparent magnitudes 3.00 and 4.00, respectively, form the base of the triangle and the yellow-white Alpha Trianguli, of magnitude 3.41, the apex. Iota Trianguli is a notable double star system, and there are three star systems with planets located in Triangulum. The constellation contains several galaxies, the brightest and nearest of which is the Triangulum Galaxy or Messier 33—a member of the Local Group. The first quasar ever observed, 3C 48, also lies within Triangulum's boundaries. ==History and mythology== In the Babylonian star catalogues, Triangulum, together with Gamma Andromedae, formed the constellation known as MULAPIN () "The Plough". It is notable as the first constellation presented on (and giving its name to) a pair of tablets containing canonical star lists that were compiled around 1000 BC, the MUL.APIN. The Plough was the first constellation of the "Way of Enlil"—that is, the northernmost quarter of the Sun's path, which corresponds to the 45 days on either side of summer solstice. Its first appearance in the pre-dawn sky (heliacal rising) in February marked the time to begin spring ploughing in Mesopotamia. The Ancient Greeks called Triangulum ''Deltoton'' (Δελτωτόν), as the constellation resembled an upper-case Greek letter delta (Δ). It was transliterated by Roman writers, then later Latinised as Deltotum. Eratosthenes linked it with the Nile Delta, while the Roman writer Hyginus associated it with the triangular island of Sicily, formerly known as Trinacria due to its shape. It was also called ''Sicilia'', because the Romans believed Ceres, patron goddess of Sicily, begged Jupiter to place the island in the heavens.〔 Greek astronomers such as Hipparchos and Ptolemy called it ''Trigonon'' (Τρίγωνον), and later, it was Romanized as Trigonum. Other names referring to its shape include Tricuspis and Triquetrum.〔 Alpha and Beta Trianguli were called ''Al Mīzān'', which is Arabic for "The Scale Beam".〔 In Chinese astronomy, Gamma Andromedae and neighbouring stars including Beta, Gamma and Delta Trianguli were called ''Teen Ta Tseang Keun'' (天大将军, "Heaven's great general"), representing honour in astrology and a great general in mythology.〔 Later, the 17th-century German celestial cartographer Johann Bayer called the constellation Triplicitas and Orbis terrarum tripertitus, for the three regions Europe, Asia, and Africa. Triangulus Septentrionalis was a name used to distinguish it from Triangulum Australe, the Southern Triangle.〔 Polish astronomer Johannes Hevelius excised three faint stars—6, 10 and 12 Trianguli—to form the new constellation of Triangulum Minus in his 1690 ''Firmamentum Sobiescianum'', renaming the original as Triangulum Majus. The smaller constellation was not recognised by the International Astronomical Union (IAU) when the constellations were established in the 1920s. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Triangulum」の詳細全文を読む スポンサード リンク
|