Alpheratz
Where is Alpheratz?
Look south, about 68° up at 00:15 in Andromeda.
- Rises
- 15:08
- Highest
- 00:11
- Sets
- 09:15
- Best after dark
- 00:15 · 68°
Can I see Alpheratz tonight?
From London tonight, Alpheratz is above the horizon all night. It’s highest after dark at 00:15, in the south at 68°.
At magnitude 2.1 it is visible by eye, even from many towns, when the sky is clear.
This is position and timing only: clouds, haze and light pollution aren’t included.
What does Alpheratz look like?
Alpheratz looks blue-white to the eye (color is easier to see in binoculars). Its spectral type is B8IV-VHgMn: hot blue-white subgiant (much hotter than the Sun).
Eyes
A bright white star at the corner of a large square of stars.
Binoculars
A bright point. Andromeda’s chain of stars leads from it toward the Andromeda Galaxy.
Telescope
A point of light. The Andromeda Galaxy is the real reason to explore this area.
About Alpheratz
Alpheratz is the brightest star in Andromeda and also marks the northeast corner of the Great Square of Pegasus. It is shared between the two constellations: it belongs officially to Andromeda.
It is a blue-white star about 97 light-years away, with an unusual chemical makeup rich in mercury and manganese.
Alpheratz is a close pair of stars orbiting each other about every 97 days. Its unusual chemistry, rich in mercury and manganese, makes it one of the brightest stars of its kind.
Its name comes from the Arabic for “the navel of the horse”, a reminder that it once was counted as part of Pegasus.
In Greek mythology, Andromeda was a princess chained to a rock as an offering to a sea monster and rescued by Perseus.
The Great Square of Pegasus is a useful sky-quality test: under dark skies you can count many faint stars inside it, while from a city you may see none.
Alpheratz in Andromeda
Questions
How do I find the Andromeda Galaxy from Alpheratz?
Sources: SkyMate; Wikidata (CC0). Positions computed for your place and time with astronomy-engine. Data & Licences