Diagram caption: The constellation Triangulum with its bright stars and surrounding constellations. Triangulum is surrounded by (going clockwise from the top): Andromeda, Pisces, Aries and Perseus.

Triangulum is a northern constellation and thus the whole constellation is visible at some point in the year throughout the northern hemisphere. The whole constellation is also visible from equatorial and most temperate regions of the southern hemisphere. Triangulum is best viewed in the evening in the northern hemisphere winter and southern hemisphere summer.

The Triangulum Galaxy M33 lies in the constellation. This spiral galaxy is the third largest member of the local group of galaxies after the Andromeda Galaxy and Milky Way. It is marked here with a red ellipse.

The y-axis of this diagram is in degrees of declination with north as up and the x-axis is in hours of right ascension with east to the left. The sizes of the stars marked here relate to the star's apparent magnitude, a measure of its apparent brightness. The larger dots represent brighter stars. The Greek letters mark the brightest stars in the constellation. These are ranked by brightness with the brightest star being labeled alpha, the second brightest beta, etc., although this ordering is not always followed exactly. The dotted boundary lines mark the IAU's boundaries of the constellations and the solid green lines mark one of the common forms used to represent the figures of the constellations. The blue line at the bottom left of the diagram marks the ecliptic. Neither the constellation boundaries, nor the lines joining the stars, nor the ecliptic, appear on the sky.

Diagram credit: Adapted by the IAU Office of Astronomy for Education from the original by the IAU and Sky & Telescope. Credit Link

Diagram translation status: Not yet approved by a reviewer
Diagram translators: An automated transliteration from the simplified Chinese translation by -
Related glossary terms: 仙女座 , 仙女座星系 , 天球坐標 , 星座 , 漩渦星系 , 白羊座 , 視星等 , 赤經（RA） , 赤緯 , 銀河系 , 雙魚座
Categories: Naked Eye Astronomy

Diagram license: Creative Commons 姓名標示 4.0 國際 (CC BY 4.0) Creative Commons 姓名標示 4.0 國際 (CC BY 4.0) icons