What kind of star is Altair?
Altair, catalogued as Alpha Aquilae (α Aql), appears in the official constellation Aquila. Its apparent visual magnitude is 0.76, while its estimated distance is about 16.7 light-years. Astronomers classify the object as A7 Vn. 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.
Altair rotates at more than 200 kilometres per second near its equator and finishes a turn in about ten hours, compared with nearly a month for the Sun. Centrifugal effects give it an oblate outline, while gravity darkening makes the compact poles hotter and brighter than the expanded equator. Long-baseline interferometers first measured the asymmetric diameter and later reconstructed surface temperature structure rather than merely inferring it from a spectrum. Altair is a young A-type main-sequence star only about 16.7 light-years away. It also exhibits low-amplitude pulsations characteristic of Delta Scuti variables. Because rotation changes the temperature visible from different latitudes, a single spectral classification cannot convey the whole surface of the star.
The coordinate pair RA 19h 50m 47.00s, Dec +08° 52′ 05.96″ 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.
Altair data at a glance
| Proper name | Altair | Catalogue designation | Alpha Aquilae (α Aql) |
|---|---|---|---|
| Constellation | Aquila | Apparent magnitude | 0.76 |
| Spectral or system type | A7 Vn | Estimated distance | about 16.7 light-years |
| Right ascension (J2000) | 19h 50m 47.00s | Declination (J2000) | +08° 52′ 05.96″ |
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 Altair
From Arabic al-nasr al-ṭāʾir, “the flying eagle.”
Altair's Mediterranean eagle imagery is only one cultural reading. In the East Asian Cowherd and Weaver Girl tradition, the star represents the cowherd Niulang, separated from Vega's weaving maiden by the celestial river of the Milky Way. The annual Qixi narrative makes their placement meaningful in a way independent of the Greek Aquila. In modern technology, the Altair 8800 computer borrowed the star's name and helped catalyse early personal computing.
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 Altair
Follow the Milky Way from Cygnus toward Aquila. Altair is the bright middle star in a short three-star line flanked by Tarazed and Alshain; no telescope is needed.
Visible from most inhabited latitudes; prominent on northern summer and autumn 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
- Look from June through October; Altair is the southernmost Summer Triangle vertex.
- Identify the short straight line Tarazed–Altair–Alshain rather than relying on brightness alone.
- Compare Altair with more distant Deneb: Altair appears brighter despite being intrinsically far less luminous.
- Its flattened photosphere cannot be resolved with an amateur telescope; use the linked interferometric view for that scale.
Interesting facts about Altair
- Altair forms the Summer Triangle with Vega and Deneb.
- It is among the nearest naked-eye first-magnitude stars.
- It completes a rotation in roughly ten hours and spins at more than 200 kilometres per second near its equator.
- Rapid rotation makes Altair measurably wider at the equator than at the poles.
- Its hotter poles and cooler equator make it a textbook example of gravity darkening.
Continue from Altair into the night sky
Use the Aquila 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.