Located in the southern celestial hemisphere, Triangulum Australe is a small constellation. The name is Latin for “the southern triangle”, which distinguishes it from the northern sky constellation Triangulum. Triangulum Australe is derived from the almost equilateral pattern of its three brightest stars.

It was first depicted on a celestial globe as Triangulus Antarcticus by Petrus Plancius in 1589, with later depictions being more accuracaate as more was known about the constellation. The current name was first seen in the 1603 Uranometria by Johann BayerThe French explorer and astronomer Nicolas Louis de Lacaille would later chart and give the brighter stars their Bayer designations in 1756.

	Applicable Information
Visibility In Pacific Northwest	Not visible in the Pacific Northwest
Best Times To View	Not visible in the Pacific Northwest
Right Ascension	14h 56.4m to  17h 13.5m
Declination	−60.26° to −70.51°
Area	110 square degrees
Main Stars	3
Brightest Object	α TrA (Atria)
Meteor showers	0
Messier objects	0
Neighboring Constellations	Norma, Ara, Circinus, Apus

History

Exploring the southern hemisphere in the 16th century, Italian navigator Amerigo Vespucci began to recognize the stars. He used this knowledge to create a now lost catalogue and descriptions of said stars for his patron king Manuel I of Portugal, which is now lost. In these writings, Vespucci wrote descriptions of the southern stars that made a triangle, which can either be the modern constellations of Triangulum Australe or Apus.

These descriptions were sent to and published by a Florence native Lorenzo di Pierfrancesco de’ Medici in 1504 as Mundus Novus in 1504. The first depiction of the constellation was provided in 1589 by Flemish astronomer and Petrus Plancius, It was first called Triangulus Antarcticus and incorrectly portrayed to the south of Argo Navis. Triangulum Australe was more accurately depicted in Johann Bayer’s celestial atlas Uranometria in 1603, where it was also given its current name.

In his 1756 star map of the southern stars, Nicolas Louis de Lacaille portrayed the constellation of Triangulum Australe as a surveyor’s level in a set of draughtsman’s instruments. Bode would give the constellation an alternate name of Libella in his Uranographia.

Stars

In defining the constellation, Lacaille gave twelve stars Bayer designations of Alpha through to Lambda. There are 2 stars close together called Eta, although one of these is now known by its Henry Draper catalogue number, while Lambda was later dropped due to its dimness.

Triangulum Australe contains several cepheid variables, all of which are too faint to be seen with the naked eye.

Triangulum Australe has few deep-sky objects, which includes 1 open cluster and several planetary nebulae and faint galaxies. NGC 6025 is an open cluster with around 30 stars, which range from the 7th to 9th magnitude.

Make sure to check out other articles on the site, including a brief introduction to constellations, other constellation articles, and more!