Triangulum Australe Constellation | Facts About The Southern Triangle

Triangulum Australe is a constellation best seen by those in the Southern hemisphere. It’s quite a small constellation, surrounded by four others; Ara on the East, Circinicus on the West, Apa to it’s South and Norma just above it. It is generally quite easy to identify, as it’s brightest star, Alpha Trianguli Australis, is one of the top 50 brightest in the sky. Let’s look at some facts about the constellation.

  • Bordered By; Norma, Ara, Circinicus, Apus.
  • Named after; The Southern Triangle
  • Declination; -60°
  • Brightest Star; Alpha Trianguli Australis
  • Best seen; September
  • Size rank; 83rd
  • Constellation family; Hercules
  • Pronunciation; TRY-ANG-GUE-LUM OS-TRAL

What is Triangulum Australe named after?

Triangulum Australe takes it’s name from the Latin for the “Southern Triangle”. Of course, it was given the Southern name to differentiate it from the Triangulum visible in the Northern hemisphere.

Who founded the Triangulum Australe Constellation?

Triangulum Australe has first been noted down by Italian astronomer and navigator Amerigo Vespucci, who travelled through the Southern hemisphere noting down his findings. However, this may have actually been the constellation Apus. The first definitive depiction of this constellation was that of Petrus Plancius, the Dutch astronomer.

How can I see Triangulum Australe in the sky?

Of course, it’s best to view Triangulum Australe in the Southern Hemisphere, as it has a declination of -60° to -70.

Main Stars in Triangulum Australe

  • Alpha Trianguli Australis (α) – The brightest star in this constellation is Alpha Trianguli Australis also referred to as Atria. It’s estimated to have a diameter that is 130x that is the Sun, and 5500x it’s brightness, which is a lot for a star. It is only 48 million years old, too.
  • Beta Trianguli Australis (β) – This star is a double star, which is different to a binary star system that we see in most constellations, as this is just two stars close together. It’s estimated to be 40 light years away from Earth.
  • Gamma Trianguli Australis (γ) – Gamma Trianguli Australis is the third brightest star in this constellation, and makes up the final point of the star. It is a singular star with a white hue, and it also appears on the Brazilian flag, along with Alpha and Beta.
  • Delta Trianguli Australis (δ) – Delta Trianguli Australias is a yellow hued singular star, with an estimated 606 light years distance from the Earth.
  • Epsilon Trianguli Australis (ε) – This star is the fifth brightest star in the constellation, but it is still visible without using a telescope. It;s estimated to be 91x the luminosity of the Sun.
  • Zeta Trianguli Australis (ζ) – Zeta Trianguli Australis is almost 40 light years distance from us, and it’s a spectroscopic binary, meaning that it is two stars, but we cannot see them clearly and only know they are there based on their reflection.
  • Kappa Trianguli Australis (κ) – Kappa Trianguli Australis is a yellow supergiant estimated to be 1200 light years away from the Earth.
  • Iota Trianguli Australis (ι) – Iota Trianguli Australis is part of a binary star system, made up form a yellow white star with another unidentifiable one.


Triangulum Australe is the Southern Hemisphere’s answer to the constellation Triangulum, and it’s a similar size, too. It is made up of quite a few stars, though the traditional Alpha, Beta and Gamma make up the three points of the triangle.