The constellation of the Southern Triangle (lat. Triangulum Australe) is composed of the stars Atria (magnitude 1.9), Betria (magnitude 3) and Gatria (magnitude 3). It is easier to recognize than the opposite constellation Triangulum of the northern hemisphere.
How to spot Triangulum Australe
With 110 square degrees, the constellation extends over the southern hemisphere and is best seen during the summer. Triangulum Australe is located south of Norma, west of Ara, east of Circinus and north of Apus.
Triangulum Australe was already mentioned at the beginning of the 16th century in the travelogues of Spanish and Portuguese explorers. At the end of the 16th century, a Dutch fleet traveled to the legendary Spice Islands to create new trade relationships. Under Captain Keyser, the positions of 135 stars were measured during this journey, which were later included by Peter Plancius in his sky maps. From these he recognized twelve new constellations, including "Den Zuyder Trianghel". A few years later, the constellation was recorded as the "Triangulum Australe" in the new Sky Atlas.