Altair
HIP 97649; Alpha Aquilae; 53 Aquilae
About Altair
Description
Altair is the twelfth brightest star in the sky at magnitude 0.77, a white main-sequence star of spectral type A7V located only 16.7 light-years from Earth. It rotates very rapidly — completing one full rotation in about 10 hours compared to the Sun's 25 days — causing it to be measurably oblate. Its luminosity is about 11 times solar.
Observing Tips
Altair is the southernmost vertex of the Summer Triangle, flanked by two dimmer stars (Beta and Gamma Aquilae) that form a distinctive line. It is easy to find in the summer and autumn evening sky. Its slightly yellowish-white color and flanking stars make it instantly recognizable. Best observed June through November.
History
The name Altair comes from the Arabic 'al-nasr al-ta'ir,' meaning 'the flying eagle.' In the East Asian legend of Qixi (the Chinese Valentine's Day), Altair represents the cowherd separated from his beloved weaver girl (Vega) by the Milky Way, allowed to meet once a year. Altair was one of the first stars to be directly imaged by interferometry, in 2007.
Fun Facts
The 2007 interferometric image of Altair was one of the first resolved images of a main-sequence star other than the Sun, clearly showing its oblate shape caused by rapid rotation. Altair's equator bulges out about 22% more than its poles.
Observe
1Physical Properties
Position & Identifiers
2How easy to split?
| Telescope | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| 80 mm refractor 80mm refr. | Medium+ | Medium | Medium |
| 150 mm Newton 150mm Newt. | Easy | Easy | Medium+ |
| Celestron C8 (203 mm SCT) C8 203mm | Easy | Easy | Easy |
Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs
3Visibility
Set a location in User Settings to see visibility data.
4Multiple Star System B,D: optical
Eyepiece View
A: 0.8 · B: 9.8 · Sep: 195.8″ · PA: 286° · N up, E left
Resolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 2.3″
Explore
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Size Comparison
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Compare Stars
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Stellar Lifecycle
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Spectral Classification
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Hertzsprung-Russell Diagram
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Blackbody Spectrum
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Stellar Absorption Spectrum
Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.
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Stellar Fusion
Discover
14Stellar Notes
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Light Travel Time Machine
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Relativistic Travel
Survey Image
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Nearby in the Sky
Other targets within a few degrees — pan your scope a little and keep exploring.
Visibility scores assume a 150 mm Newton at Bortle 4.
