The Constellation Triangulum

by Dominic Ford
Triangulum Triangulum
The constellation Triangulum. Roll mouse over to see labels.
Source: Stellarium.

Triangulum is a small yet ancient northern constellation, nestling between Andromeda and Aries. It appears highest in the evening sky in the months around October.

Comprising simply of a triangle of two third magnitude stars and one fourth magnitude star, it is far from conspicuous. In ancient Greece it was known as ‘Deltoton’ because it resembled a capital delta (Δ).

Although it is home to only one bright deep sky object, it is a significant one. The Triangulum Galaxy (M33) is a member of the Local Group of galaxies, and the second-closest galaxy of comparable size to our own.

M33 is a spiral galaxy like our own, and orientated in an almost face-on orientation so that its spiral structure is finely displayed. However, this also means its light is spread over a large sky area, comparable in size to the full moon. The slightest light pollution makes it quite impossible to make out its diffuse light.

Date First Appeared
Ancient
Sky Area
0.3% of the sky
131.8 square degrees
Messier Objects
Triangulum contains the following Messier object: M33.
Caldwell Objects
Triangulum contains no Caldwell objects
Neighbors
The following constellations neighbor Triangulum: Andromeda, Aries, Perseus, Pisces.
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Brightest Objects in Triangulum

Stars Open Clusters Globular Clusters Galaxies
Stars Open Clusters Globular Clusters Galaxies
β-Tri (mag 3.0) IC 1800 (mag 0.0) NGC 661 (mag 0.0)
Mothallah (mag 3.4) NGC 735 (mag 0.0)
γ-Tri (mag 4.0) NGC 769 (mag 0.0)
δ-Tri (mag 4.9) NGC 798 (mag 0.0)
14-Tri (mag 5.2) NGC 974 (mag 0.0)
HD (mag 5.2) NGC 1066 (mag 0.0)
7-Tri (mag 5.2) NGC 587 (mag 0.0)
10-Tri (mag 5.3) NGC 739 (mag 0.0)
12-Tri (mag 5.3) NGC 780 (mag 0.0)
15-Tri (mag 5.4) NGC 807 (mag 0.0)
ε-Tri (mag 5.5) NGC 865 (mag 0.0)
11-Tri (mag 5.6) NGC 968 (mag 0.0)
HD 10390 (mag 5.6) NGC 1002 (mag 0.0)
HD 11007 (mag 5.8) IC 171 (mag 0.0)
HD 15755 (mag 5.8) NGC 621 (mag 0.0)
HD 11928 (mag 5.9) NGC 688 (mag 0.0)
13-Tri (mag 5.9) NGC 785 (mag 0.0)
HD 10348 (mag 6.0) NGC 826 (mag 0.0)
HD 16187 (mag 6.1) NGC 971 (mag 0.0)
5-Tri (mag 6.2) NGC 1061 (mag 0.0)
HD 16220 (mag 6.2) IC 227 (mag 0.0)
HD 15464 (mag 6.3) IC 1815 (mag 0.0)
HD 10588 (mag 6.3) NGC 579 (mag 0.0)
HD 9298 (mag 6.4) NGC 666 (mag 0.0)
HD 14373 (mag 6.5) NGC 804 (mag 0.0)

Ashburn

Latitude:
Longitude:
Timezone:

39.04°N
77.49°W
EDT

Color scheme