Great Square of Pegasus
The Great Square of Pegasus is an asterism, a star pattern that is not one of the 88 official constellations, made of four stars in Andromeda and Pegasus. Its brightest star is Alpheratz (magnitude 2.06), and it is best seen in the evening in October.
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How to use it
The fourth corner, Alpheratz, officially belongs to Andromeda; the square is a signpost to the Andromeda Galaxy (M31).
How to find the Great Square of Pegasus
From 40° N (the USA, southern Europe, Japan) it is highest in the south, about 72° above the horizon, in October evenings. From 35° S (Australia, South Africa, Argentina) it reaches about 33° in the north.
Stars of the Great Square of Pegasus
| Star | Designation | Magnitude | Distance | Constellation |
|---|---|---|---|---|
| Alpheratz | α Andromedae | 2.06 | 97 ly | Andromeda |
| Scheat | β Pegasi | 2.42 | 199 ly | Pegasus |
| Markab | α Pegasi | 2.49 | 140 ly | Pegasus |
| Algenib | γ Pegasi | 2.83 | 469 ly | Pegasus |
Questions about the Great Square of Pegasus
Is the Great Square of Pegasus a constellation?
No. The Great Square of Pegasus is an asterism: its stars belong to Andromeda and Pegasus, two of the 88 constellations defined by the International Astronomical Union.
What is the brightest star of the Great Square of Pegasus?
Alpheratz, with an apparent magnitude of 2.06, about 97 light-years away.
When can I see the Great Square of Pegasus?
It is highest in the evening sky in October.
Other asterisms
Big DipperUrsa Major
Little DipperUrsa Minor
Orion's BeltOrion
Summer TriangleLyra, Aquila and Cygnus
Winter TriangleCanis Major, Canis Minor and Orion
Winter HexagonCanis Major, Auriga, Orion, Canis Minor, Taurus and Gemini
TeapotSagittarius
Northern CrossCygnus
Spring TriangleBoötes, Virgo and Leo
Sickle of LeoLeo
KeystoneHercules
False CrossCarina and Vela
Southern PointersCentaurus