Triangulum Australe
The southern sky's tight, bright triangle
Best on June–August evenings · far-southern sky.
Triangulum Australe, the Southern Triangle, is a small but surprisingly prominent constellation tucked into the rich Milky Way south of Norma and east of Circinus. Its three named stars form a neat, compact triangle that stands out clearly in dark skies, making it one of the easier southern patterns to identify despite its modest size.
How to find it
On summer evenings in the southern hemisphere, look high in the southern sky and find the bright pointer stars Alpha and Beta Centauri — from there, sweep east and slightly south toward the luminous band of the Milky Way. The Southern Triangle sits in that star-rich region; once you spot its brightest star Atria, the tight three-star shape snaps into focus quickly.
Brightest stars
Atria (α TrA) leads the triangle at magnitude 1.92, making it a genuine first-magnitude beacon and the unmistakable anchor of the pattern. Betria (β TrA) at magnitude 2.85 and Gatria (γ TrA) at 2.89 complete the triangle, closely matched and both comfortably bright to the naked eye.
Worth seeing
The triangle itself is the reward — three stars arranged in a compact, well-defined shape set against one of the brightest stretches of the Milky Way, giving the whole region a stunning backdrop on a dark southern night.
Frequently asked
When is Triangulum Australe visible?
Summer evenings, roughly June through August, when it rides high in the southern sky. It's a deep-southern constellation best seen from the southern hemisphere and tropical latitudes.
What are the main stars in Triangulum Australe?
Three named stars form the triangle: Atria (magnitude 1.92) is the brightest, with Betria (2.85) and Gatria (2.89) completing the shape — all three visible to the naked eye without any trouble.
Which hemisphere is Triangulum Australe in?
It's a southern hemisphere constellation, sitting well below the celestial equator. Observers north of the subtropics will struggle to see it, but from southern latitudes it passes high overhead on summer evenings.
Nearby constellations
Crux · Centaurus · Scorpius · Carina · Sagittarius · Libra · Corvus · Ophiuchus