Triangulum Australe
What is Triangulum Australe?
Constellations· Southern winter · a crisp triangle southeast of Alpha Centauri. The southern triangle, larger and brighter than its northern namesake. Three stars form an almost perfect triangle, making it one of the easiest southern constellations to spot, and its leader Atria is a southern guide star.
📍 Visible from where you are right now — computed in your browser
bearing · altitude · rise time · best time tonight
Where Triangulum Australe is in your sky right now: https://nowsky.org/solar/sky?sel=con:Triangulum Australe — location and time set automatically, no login.
Stars of the figure
| Star | Magnitude |
|---|---|
| Atria | 1.9 |
The 1 brightest of the 3 stars used in the figure (3 lines). Lower magnitude means brighter.
Constellation basics
| Season | Jun–Jul evenings; never visible from Korea |
|---|---|
| Brightest star | Atria, mag 1.9 |
| How to find | a short hop southeast of Alpha Centauri and Hadar |
| Area rank | 83rd of 88 |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Frequently asked
- When can I see Triangulum Australe?
- Jun–Jul evenings; never visible from Korea.
- How do I find Triangulum Australe?
- a short hop southeast of Alpha Centauri and Hadar.
- What is the brightest star in Triangulum Australe?
- Atria, magnitude 1.9.
- Where is Triangulum Australe in the sky right now?
- Open the sky view for your location and time and it shows the position in the sky right now.
The cluster Lacaille found, and a chief star named only in 2016
On the northern edge of Triangulum Australe lies NGC 6025, an open cluster Lacaille found from the Cape in 1752. A loose gathering of some sixty stars 2,700 light-years away, it shows well in binoculars and is the first thing southern observers look for in this constellation. Lacaille put it in the first class of his catalogue, "nebulae without stars", though it is in fact a group of stars.
The chief star, Atria, received its official name from the International Astronomical Union only in 2016. It is a modern contraction of Alpha Trianguli Australis; in a southern constellation with no old Arabic or Latin names, the abbreviation used in navigation almanacs simply became the name. The bright star and the cluster that the northern Triangle lacks are both present in the southern one.
The constellation in depth
Triangulum Australe is one of the twelve southern constellations born of the Dutch navigators' observations in the 1590s and published in Bayer's atlas of 1603. It pairs with the small northern Triangulum, but its stars are far brighter, so in the south it is the better known of the two. Early sailors used this triangle together with Alpha Centauri to orient themselves in the southern sky.
Its leading star Atria, alpha Trianguli Australis, is an orange giant of magnitude 1.9 about 400 light-years away; the name is a modern contraction of 'alpha TrA'. Beta and gamma are third-magnitude white stars. On the edge of the Milky Way, the open cluster NGC 6025 shows well in binoculars, and distant galaxy clusters in this direction are objects of study.
At declinations of −60° to −70° it is never visible from Korea but stays above the horizon almost all year in the southern hemisphere. On June and July evenings, when Alpha Centauri and Hadar are high, shift your gaze a little southeast to find the crisp triangle. In the Sky view, set Sydney or Cape Town on a July evening.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.