A little constellation called Triangulum Australe can be found in the very southern celestial hemisphere. Its moniker, "the southern triangle," comes from the sharp, nearly equilateral pattern formed by its three brightest stars and distinguishes it from Triangulum in the northern sky. Triangulus Antarcticus, which Petrus Plancius initially identified on a celestial globe in 1589, was later given its modern name by Johann Bayer in his 1603 Uranometria. In 1756, the French traveller and astronomer Nicolas Louis de Lacaille catalogued and assigned the Bayer names to the brighter stars.
The brightest star in the constellation and the 42nd-brightest star in the night sky is Alpha Trianguli Australis, also known as Atria, a second-magnitude orange giant. The two white main sequence stars Beta and Gamma Trianguli Australis complete the triangle. Deep-sky objects are not particularly noticeable despite the Milky Way's location and the constellation's abundance of stars. The open cluster NGC 6025 and the planetary nebula NGC 5979 are noteworthy objects. The gravitational nucleus of the Laniakea Supercluster, which contains the Milky Way galaxy, known as The Great Attractor, is on the border between the constellation Norma and Triangulum Australe. |
A minor constellation known as Triangulum Australe is surrounded by the constellations Norma to the north, Circinus to the west, Apus to the south, and Ara to the east. Only Circinus stands between it and the Pointers (Alpha and Beta Centauri). (Moore 2005) Since the constellation is within the Milky Way, it has a large number of stars. (Inglis 2004) It can be seen as an equilateral triangle. Triangulum Australe is circumpolar from much of the southern hemisphere, but it is too far south in the celestial southern hemisphere to be seen from Europe. (Inglis 2004) The International Astronomical Union chose the three-letter abbreviation "TrA" for the constellation in 1922. (Russell 1922) The official constellation borders were established in 1930 by Belgian astronomer Eugène Delporte and are represented by an 18-segment polygon. These borders have right ascension coordinates between 14h 56.4m and 17h 13.5m in the equatorial coordinate system, and declination coordinates between 60.26° and 70.51°. At nine o'clock on August 23 of each year, Triangulum Australe ends. (James 2011)
History
Amerigo Vespucci, an Italian explorer, travelled to the New World at the start of the 16th century. He developed his star-spotting skills in the southern hemisphere and created a lost catalogue for his patron King Manuel I of Portugal. Vespucci also described the southern stars in his inventory, including a triangle that could either be Triangulum Australe or Apus. This was addressed to Lorenzo di Pierfrancesco de' Medici, his patron in Florence, and was printed as Mundus Novus in 1504. (Kanas 2007) The constellation was first shown in 1589 by Flemish astronomer and clergyman Petrus Plancius on a 32+12 cm diameter celestial globe published in Amsterdam by Dutch cartographer Jacob Floris van Langren, where it was incorrectly shown to the south of Argo Navis and given the incorrect name Triangulus Antarcticus. The term "Den Zuyden Trianghel" was created by Dutch explorer Frederick de Houtman and his pupil Petrus Keyzer. (Wagman 2003) Johann Bayer's celestial atlas Uranometria, published in 1603, more precisely represented Triangulum Australe and gave it its present name. (Moore & Tirion 1997)
In his 1756 map of the southern stars, Nicolas Louis de Lacaille represented the constellations of Norma, Circinus, and Triangulum Australe as a set square and ruler, a compass, and a surveyor's level, respectively. German Johann Bode gave it the alternative name of Libella in his Uranographia, which also depicted it as a surveyor's level.
The Three Patriarchs—Abraham, Isaac, and Jacob—were represented by the three primary stars, according to German poet and author Philippus Caesius (with Atria as Abraham). (Motz & Nathanson 1991) The Triangulum Australe stars were seen by the Wardaman people of Australia's Northern Territory as the tail of the Rainbow Serpent, which extended from close to Crux across to Scorpius. The Rainbow Serpent "gives Lightning a nudge" overhead in October to start the rainy season in November. (Harney & Cairns 2004)
Amerigo Vespucci, an Italian explorer, travelled to the New World at the start of the 16th century. He developed his star-spotting skills in the southern hemisphere and created a lost catalogue for his patron King Manuel I of Portugal. Vespucci also described the southern stars in his inventory, including a triangle that could either be Triangulum Australe or Apus. This was addressed to Lorenzo di Pierfrancesco de' Medici, his patron in Florence, and was printed as Mundus Novus in 1504. (Kanas 2007) The constellation was first shown in 1589 by Flemish astronomer and clergyman Petrus Plancius on a 32+12 cm diameter celestial globe published in Amsterdam by Dutch cartographer Jacob Floris van Langren, where it was incorrectly shown to the south of Argo Navis and given the incorrect name Triangulus Antarcticus. The term "Den Zuyden Trianghel" was created by Dutch explorer Frederick de Houtman and his pupil Petrus Keyzer. (Wagman 2003) Johann Bayer's celestial atlas Uranometria, published in 1603, more precisely represented Triangulum Australe and gave it its present name. (Moore & Tirion 1997)
In his 1756 map of the southern stars, Nicolas Louis de Lacaille represented the constellations of Norma, Circinus, and Triangulum Australe as a set square and ruler, a compass, and a surveyor's level, respectively. German Johann Bode gave it the alternative name of Libella in his Uranographia, which also depicted it as a surveyor's level.
The Three Patriarchs—Abraham, Isaac, and Jacob—were represented by the three primary stars, according to German poet and author Philippus Caesius (with Atria as Abraham). (Motz & Nathanson 1991) The Triangulum Australe stars were seen by the Wardaman people of Australia's Northern Territory as the tail of the Rainbow Serpent, which extended from close to Crux across to Scorpius. The Rainbow Serpent "gives Lightning a nudge" overhead in October to start the rainy season in November. (Harney & Cairns 2004)
Deep-sky Objects
Main stars - 3
Bayer stars - 10
Stars with planets - 1
Stars brighter than magnitude 3.00 - 3
Stars within 32 Ly - 0
Messier objects - 0
Meteor showers - 0
Bordering
constellations
- NGC 6025 – Open Cluster
- NGC 5979 – Planetary Nebula
- NGC 5938 – Spiral Galaxy
- NGC 6101 – Globular Cluster
Main stars - 3
Bayer stars - 10
Stars with planets - 1
Stars brighter than magnitude 3.00 - 3
Stars within 32 Ly - 0
Messier objects - 0
Meteor showers - 0
Bordering
constellations
- Norma
- Ara
- Circinus
- Apus