Summer Triangle

The Summer Triangle is an asterism, a star pattern that is not one of the 88 official constellations, made of three stars in Lyra, Aquila and Cygnus. Its brightest star is Vega (magnitude 0.03), and it is best seen in the evening in September.

Free to use with credit: Atlas of the Sky (constellationmap.org), CC BY 4.0 · More

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<a href="https://constellationmap.org/asterisms/summer-triangle/"><img src="https://constellationmap.org/img/asterisms/summer-triangle-star-map.png" alt="Summer Triangle star map: the three stars Vega, Altair and Deneb connected by lines and labeled, with the surrounding constellations" width="800" height="800" loading="lazy"></a>
<br><small><a href="https://constellationmap.org/asterisms/summer-triangle/">Summer Triangle</a> · Atlas of the Sky (constellationmap.org), <a href="https://creativecommons.org/licenses/by/4.0/">CC BY 4.0</a></small>

How to find the Summer Triangle, step by step

Vega, Deneb and Altair.

On summer and early autumn evenings look high in the east to overhead (from mid-northern latitudes).
The brightest star there is Vega. Deneb is to its lower left (east) and Altair farther to the south.
The three form a large triangle; the Milky Way runs through it from Cygnus down to Aquila.

How to use it

Vega is the brightest of the three and stands almost overhead on summer evenings at mid-northern latitudes; the Milky Way runs through the triangle.

How to find the Summer Triangle

From 40° N (the USA, southern Europe, Japan) it is highest in the south, about 81° above the horizon, in September evenings. From 35° S (Australia, South Africa, Argentina) it reaches about 24° in the north.

Stars of the Summer Triangle

Star	Designation	Magnitude	Distance	Constellation
Vega	α Lyrae	0.03	25 ly	Lyra
Altair	α Aquilae	0.77	17 ly	Aquila
Deneb	α Cygni	1.25	1,640 ly	Cygnus

Questions about the Summer Triangle

Is the Summer Triangle a constellation?

No. The Summer Triangle is an asterism: its stars belong to Lyra, Aquila and Cygnus, three of the 88 constellations defined by the International Astronomical Union.

What is the brightest star of the Summer Triangle?

Vega, with an apparent magnitude of 0.03, about 25 light-years away.

When can I see the Summer Triangle?

It is highest in the evening sky in September.