Triangulum

The Triangle

A small, narrow triangle of stars near Andromeda that holds the Triangulum Galaxy, a large spiral galaxy visible in dark skies.

Chart drawn as the sky looks when you face the constellation: north is up and east is to the left. Dot size shows brightness, and color hints at temperature. The connecting lines are one common stick figure; other traditions draw them differently.

Best season: Autumn
Best months: October through January, high in the south on autumn evenings
Visibility: Visible from everywhere in the United States, best from dark sites
Abbreviation: Tri

How to find it

Find Almach in Andromeda and Hamal in Aries. Triangulum sits roughly midway between them.
Look for a long, thin triangle of three stars.

Brightest stars

Beta Trianguli
Mothallah

What to look for

M33 as a faint, large smudge in a very dark sky. Binoculars help.

Binocular and telescope targets

Triangulum Galaxy (M33): a large face-on spiral galaxy about 2.7 million light-years away; its light is spread thin, so it needs a dark sky

Using it to find other things

Triangulum lies between Andromeda and Aries.

About this constellation

Triangulum itself is nothing special, a thin triangle of three stars. Its main attraction is M33, the third-largest galaxy in our Local Group after the Milky Way and Andromeda.

M33 is a challenge because its light is spread out over a large area. A dark sky and binoculars make it much easier to see.

Related guides

Visibility depends on your latitude, the date, and the time of night. The months above assume a typical evening from the contiguous United States, so use a planetarium app to confirm what is up tonight. Never look at the Sun through binoculars or a telescope without a proper solar filter.

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