What kind of star is Markab?
Markab, catalogued as Alpha Pegasi (α Peg), appears in the official constellation Pegasus. Its apparent visual magnitude is 2.48, while its estimated distance is about 133 light-years. Astronomers classify the object as A0 IV. These labels describe temperature, luminosity class or system components; they should not be read as a claim that every naked-eye point is a single isolated star.
Alpha Pegasi is an A0 subgiant approximately 133 light-years away. It has used much of the hydrogen available in its core and begun the structural changes that move a star away from the main sequence. Markab is hotter, more massive and much more luminous than the Sun, but it lacks the dramatic circumstellar environment of some other rapidly rotating A and B stars. Spectroscopic studies classify it as a useful bright standard in the autumn sky, while modern astrometry refines its distance and space motion. The four Great Square stars are not a physical group: Markab, Scheat, Algenib and Alpheratz merely align from Earth's viewpoint and lie at very different distances and evolutionary stages.
The coordinate pair RA 23h 04m 45.65s, Dec +15° 12′ 19.0″ fixes the object's direction on the celestial sphere for the J2000 reference epoch. Right ascension works like celestial longitude measured in hours, while declination works like latitude north or south of the celestial equator. Proper motion and improved measurements can refine catalogue positions, but these coordinates are sufficiently precise for a finder chart or planetarium search.
Markab data at a glance
| Proper name | Markab | Catalogue designation | Alpha Pegasi (α Peg) |
|---|---|---|---|
| Constellation | Pegasus | Apparent magnitude | 2.48 |
| Spectral or system type | A0 IV | Estimated distance | about 133 light-years |
| Right ascension (J2000) | 23h 04m 45.65s | Declination (J2000) | +15° 12′ 19.0″ |
Values are rounded for an observer-friendly overview. Consult the linked SIMBAD record for component-level identifiers, bibliography, measurement provenance and newer catalogue values.
The name Markab
From Arabic markab, commonly interpreted as “saddle” or “vehicle.” Similar Arabic roots produced several historical star names, so context matters when tracing the term.
Markab's traditional name came through Arabic star lore and medieval astronomical tables. Johann Bayer designated it Alpha Pegasi, though Epsilon Pegasi, Enif, can appear slightly brighter. The Great Square became one of the most durable wayfinding patterns in northern autumn skies, even after Alpheratz was assigned exclusively to neighbouring Andromeda. That boundary decision left three Square corners in Pegasus and one in Andromeda, despite the asterism's familiar name.
Modern professional catalogues retain identifiers such as the Bayer designation alongside a proper name. The International Astronomical Union standardizes which name belongs to which component—an important distinction for systems whose combined light looks like one star from Earth.
How to find Markab
Find the large Great Square rising in the east during northern autumn. Markab is its southwestern corner. Extend the western side southward to search for Fomalhaut, or use the Square as a broad guide into the faint zodiacal constellations below it.
Visible from most of Earth and prominent on northern autumn and southern spring evenings. Visibility on a particular night still depends on latitude, season, time, horizon obstructions, weather and local light pollution. Use the interactive atlas below to check the surrounding field before observing.
Observation checklist
- Best during September through November evenings.
- Begin with the whole Great Square rather than isolated star-hopping.
- Use a low-power binocular field to explore south into Aquarius.
- Remember Alpheratz belongs officially to Andromeda, not Pegasus.
Interesting facts about Markab
- Markab forms the Great Square's southwestern corner.
- It is an A-type subgiant, not a giant.
- The Great Square's stars are unrelated in physical space.
- Its distance is about 133 light-years.
- Alpha does not make it Pegasus's unequivocally brightest star.
Continue from Markab into the night sky
Use the Pegasus constellation guide to place this star within its larger pattern. When you are ready to observe, compare dark-sky places, find a nearby observatory, or follow our practical guide to finding a star in the night sky. Symbolically registered names are kept separately in the searchable Star-Register catalogue.
Sources and further reading
Measurements are rounded for readability. Multiple systems, variable stars and distant supergiants can have component-specific or model-dependent values. Survey panels show photographic sky fields, not the physical surface of the star.