# Markab (Alpha Pegasi)

Markab (Alpha Pegasi) is a star in the constellation Pegasus, magnitude 2.5.

**A corner of the Great Square of Pegasus — a fast-spinning white star that has begun to swell.**

Markab holds up one corner of the Great Square of Pegasus, yet for an Alpha star it is surprisingly modest: two other stars in the winged horse outshine it. It is a hot white [star](https://astropilot.space/glossary/star), around 10,000 K at the surface, that has used up the hydrogen in its core and begun to swell. It is now nearly five times the Sun’s width and 165 times as luminous.

It spins hard, too — at least 130 kilometres per second at its equator, more than 60 times the Sun’s rate. Astronomers have not even settled its exact [class](https://astropilot.space/glossary/spectral-type): it has been listed as a subgiant, a main-sequence star and a giant.

The name is usually traced to the Arabic for “the saddle of the horse”. It may instead be a garbled copy of Mankib, “the shoulder of the horse”, a name that first belonged to its neighbour Scheat, Beta Pegasi.

Markab (Alpha Pegasi) is 130 light-years away: the light we see from it set off around 1895, 7 years before the Wright brothers made the first powered flight.

## Did you know?

- **A mansion of the Moon.** In ancient Indian astronomy Markab and Beta Pegasi are the chief stars of Purva Bhadrapada, the 25th nakshatra — one of the lunar mansions the Moon passes through each month.
- **The Encampment.** Chinese astronomers paired Markab with Beta Pegasi in Shì, the Encampment. Markab is its first star.
- **A namesake in the south.** The same Arabic word gave the name Markeb to a star in Vela. It is spelled differently to avoid confusion with this one.

A white star of magnitude 2.5 at the south-western corner of the Great Square of Pegasus. Compare it with orange Scheat, the corner to its north, then extend that side of the Square about 45 degrees south to reach Fomalhaut.

## When and where to see it

It is best placed in the evening sky around October, when it crosses the meridian at about 10 pm local time (around midnight in September). It can be seen from everywhere north of 75°S and never sets north of 75°N.

At its highest it stands 55° up from 50°N, 70° up from 35°N, 75° up from the equator, 40° up from 35°S.

## Facts

- Type: Star
- Constellation: Pegasus
- Designations: Alpha Pegasi, α Peg, 54 Peg, HR 8781, HD 218045, HIP 113963
- Magnitude: 2.5
- Position: RA 23h 4.8m, Dec +15° 12′ (J2000)
- Spectral type: A0IV
- Colour: white (B−V -0.04)
- Distance: 130 light-years
- Discovered: Known since antiquity

Open AstroPilot to see when Markab (Alpha Pegasi) is highest tonight from your location, how easy it is with your telescope or binoculars, and an eyepiece view. https://astropilot.space/object/markab