Triangulum - The Triangle

Triangulum is a small constellation visible in the fall and winter sky. It is located north of Aries and south of Andromeda.

History and Mythology

Triangulum is an ancient constellation. It was first named Deltotron after the Greek letter delta, a small triangle. Its name derives from the three relatively bright stars in the constellation that form a triangle.

Notable Objects

The stars Alpha, Beta, and Gamma Trianguli form a distinct triangle. Beta Trianguli is a 3rd magnitude star 125 light-years away. Gamma Triangulum is a 4th magnitude star 118 light-years away.

There are no major star clusters or nebulae in this constellation.

M 33 is the one prominent galaxy in Triangulum. It is a spectacular spiral galaxy, known as the Pinwheel Galaxy. It is seen face-on with wide, irregular spiral arms filled with dark clumps and bright knots. It is about 3 million light-years away and is a member of our local group of galaxies.

M33 can be difficult to see due to its low surface brightness. Use a low power eyepiece or binoculars on a clear, dark night.