Constellation, Southern Triangle
Triangulum Australe
A small, clear triangle of stars in the far southern sky, one of the figures of the Dutch navigators. Lacaille later pictured it as a surveyor’s level.
From New York the constellation Triangulum Australe never rises above the horizon: it belongs to the other hemisphere’s sky.
From New York the constellation Triangulum Australe never rises above the horizon: it belongs to the other hemisphere’s sky.
In the 3D sky
The sky over New York turned towards Triangulum Australe. Drag to look around.
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Evening visibility over the year
Height of the constellation’s centre above the horizon at 10 pm local time on the 15th of each month, from New York. Above about 30° it is well placed.
Name and history
Triangulum Australe, the southern triangle, is one of the twelve figures made from the observations of the Dutch navigators Pieter Dirkszoon Keyser and Frederick de Houtman at the end of the 16th century. Petrus Plancius first drew it on his globe of 1598 but left it unnamed. It first appeared in print in Johann Bayer’s atlas of 1603. Plancius had shown a southern triangle on a globe as early as 1589, but in a different place, south of Argo Navis. That earlier figure is not the one we know today. Unlike most of the Dutch figures, this one is not an animal, and it has no myth.
Nicolas Louis de Lacaille called it ‘le Triangle Austral ou le Niveau’ on his chart of 1756 and drew a plumb bob hanging from it, making it a surveyor’s level. With his compasses, Circinus, and set square, Norma, it formed a group of measuring tools. The historian R. H. Allen later moved the name ‘level’ to Norma by mistake, which confused readers for generations. Navigators named the brightest star Atria, a contraction of Alpha Trianguli Australis.
Brightest stars
| Star | Designation | Magnitude | Distance |
|---|---|---|---|
| Atria | α TrA | 1.91 | 391 light-years |
| β TrA | β TrA | 2.83 | 40 light-years |
| γ TrA | γ TrA | 2.87 | 184 light-years |
| δ TrA | δ TrA | 3.86 | 607 light-years |
| ε TrA | ε TrA | 4.11 | 202 light-years |
| ζ TrA | ζ TrA | 4.90 | 40 light-years |
Facts
| Area | about 111 square degrees (83 of 88) |
|---|---|
| IAU abbreviation | TrA |
| Sky | Southern sky |
| Origin | First shown, still unnamed, on a celestial globe by Petrus Plancius in 1598, from observations by Keyser and de Houtman |
| Stars brighter than magnitude 5 | 6 |
| Centre (J2000) | 16.1 h, -67° |
Deep-sky objects
Galaxies, clusters and nebulae brighter than magnitude 9, from the OpenNGC catalogue. Most need binoculars or a telescope and a dark sky.
| Object | Type | Magnitude |
|---|---|---|
| NGC6025 | Open cluster | 5.1 |
Boundaries: International Astronomical Union, via Astronomy Engine. Areas are computed from the boundaries by sampling (within about one percent). Names and lines: Stellarium. Stars: HYG Database. Deep-sky objects: OpenNGC. Calculated with Astronomy Engine, an open-source library verified against the US Naval Observatory and NASA JPL. Data sources
How to use this page
Choose your place and a night at the top. The answer and the 3D view show where the constellation is, when it is highest and whether it rises at all from where you are. The chart shows its stars and lines, and the tables list its brightest stars and the deep-sky objects inside it.
Frequently asked questions
When is a constellation best seen?
When it is highest in a dark sky, which the page gives for the night you pick. Each constellation is best placed in a particular season, because the stars rise about four minutes earlier every night.
Why can I not see a constellation from my place?
Constellations far south of the celestial equator never rise from northern places, and those far north never rise from southern ones. The page says when this is the case.
What are the constellation boundaries?
The International Astronomical Union divides the sky into 88 areas with official boundaries. The stick figures are only a drawing aid, the boundaries say which constellation a point in the sky belongs to.
Related guides
- How to learn the constellationsStart with one bright pattern you cannot miss, use it as a signpost to its neighbours, and come back a month later: the sky will have turned, and you will know a little more of it.
- Altitude and azimuth: finding things in the skyTwo angles tell you exactly where to look: which direction, and how high.
- Light pollution and dark skies: the Bortle scaleFrom a city centre you can count a few dozen stars. From a truly dark site you can count a few thousand, with the Milky Way bright enough to cast a shadow. The Bortle scale puts a number on the difference.
- Binoculars for stargazing: what to buy and what to look atA pair of 7x50 or 10x50 binoculars shows the craters of the Moon, the moons of Jupiter, dozens of star clusters and the Andromeda Galaxy, for a fraction of the cost of a telescope.