# Alnair (Alpha Gruis)

Alnair (Alpha Gruis) is a star in the constellation Grus, magnitude 1.7.

**The bright one of the Crane — a fast-spinning blue-white star from a young family of stars.**

Alnair is Arabic for ‘the bright one’, short for a longer name meaning ‘the bright one of the fish’s tail’. Arab astronomers counted the stars of the Crane as part of the Southern Fish; the Crane is a much younger constellation, and Alnair first appeared in a star atlas in Johann Bayer’s Uranometria of 1603.

It is a hot blue-white [star](https://astropilot.space/glossary/star) about four times the Sun’s mass and roughly 520 times as bright, spinning at 215 km/s or more at its equator. It is young, perhaps 100 million years old, and belongs to the AB Doradus moving group — a family of young stars that travel through space together. Unlike so many bright stars, it has no known companions.

Alnair (Alpha Gruis) is 100 light-years away: the light we see from it set off around 1925, around the time Edwin Hubble showed that other galaxies exist.

## Did you know?

- **A name from China.** Chinese astronomers made it the first star of Hè, the Crane, and that name gave rise to another English name for it: Ke.
- **A navigator’s star.** Alnair is one of the 58 stars selected for celestial navigation. Confusingly, a mid-20th-century almanac also gave the name Alnair to a different star, Zeta Centauri.

A bright blue-white star leading the Crane, in a sparse region of the southern sky. Compare it with Beta Gruis nearby: Alnair’s cool blue-white against Beta’s orange-red is a fine colour contrast.

## When and where to see it

It is best placed in the evening sky around September, when it crosses the meridian at about 10 pm local time (around midnight in August). It can be seen from everywhere south of 43°N and never sets south of 43°S.

At its highest it stands below the horizon from 50°N, 8° up from 35°N, 43° up from the equator, 78° up from 35°S.

## Facts

- Type: Star
- Constellation: Grus
- Designations: Alpha Gruis, α Gru, HR 8425, HD 209952, HIP 109268
- Magnitude: 1.7
- Position: RA 22h 8.2m, Dec −46° 58′ (J2000)
- Spectral type: B6V
- Colour: blue-white (B−V -0.13)
- Distance: 100 light-years
- Discovered: Known since antiquity

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