Triangulum constellation
Triangulum (the Triangle) is a constellation in the northern sky, best seen in the evening in December. Its brightest star is β Trianguli (magnitude 3.0). Triangulum covers 132 square degrees and is the 79th-largest of the 88 constellations.
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Detailed star map of Triangulum
Facts
| Latin name | Triangulum (genitive: Trianguli) |
|---|---|
| Abbreviation | Tri |
| Meaning | the Triangle |
| Area | 132 square degrees (79th of 88) |
| Location | right ascension 2.2 h, declination +32° |
| Visible from | latitudes 90° N to 53° S (whole constellation) |
| Best month | December (at about 9 pm) |
| Brightest star | β Trianguli |
| Stars brighter than magnitude 6 | 19 |
| Named stars (IAU) | 1 |
| Messier objects | M33 |
| Neighbors | Andromeda, Aries, Perseus, Pisces |
How to find Triangulum
From 40° N (the USA, southern Europe, Japan) look south in December evenings: at about 9 pm Triangulum stands highest, around 82° above the southern horizon. From 35° S (Australia, South Africa, Argentina) it is highest in the north, about 23° above the horizon. The months before and after (November and January) are also good: then it is up a couple of hours earlier or later.
Triangulum borders Andromeda, Aries, Perseus and Pisces.
Stars of Triangulum
Triangulum has 19 stars brighter than magnitude 6, the limit of the naked eye under a dark sky. These are the brightest:
| Star | Designation | Magnitude | Type | Distance |
|---|---|---|---|---|
| — | β Trianguli | 3.0 | A5III | — |
| Mothallah | α Trianguli | 3.41 | F6IV | 64 ly |
| — | γ Trianguli | 4.01 | A1Vnn | — |
Deep-sky objects in Triangulum
Triangulum contains one object from Charles Messier's catalog:
- Triangulum Galaxy (M33): spiral galaxy, 5.7 mag
Printable Triangulum map and outline
A black and white version for printing and a plain outline of the Triangulum figure, useful for school projects, worksheets and learning to recognize the shape.
History
Triangulum is one of the 48 constellations listed by Ptolemy in the Almagest (2nd century AD). Its official boundary was drawn by Eugène Delporte for the International Astronomical Union in 1930.
Questions about Triangulum
What is the brightest star in Triangulum?
β Trianguli, at magnitude 3.0.
When can you see Triangulum?
Triangulum is best seen in the evening in December. The whole constellation is visible from latitudes between 90° N and 53° S.
How many stars are in Triangulum?
19 stars in Triangulum are brighter than magnitude 6 and can be seen with the naked eye under a dark sky; 1 of them have official IAU names.
What does Triangulum mean?
Triangulum means “the Triangle” in Latin. Its abbreviation is Tri and the genitive, used in star names such as β Trianguli, is Trianguli.
