Your Guide to the Solar System and the Night Sky
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public Observing fromLocation: Greenwich, United Kingdom edit_location_alt
north SunriseRise: 4:47  
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SunsetSet: 21:06 south
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All Constellations » Grus » 

Alnair - α Gruis (alpha Gruis)

Alnair, also designated as α Gruis (alpha Gruis), is a variable and double sub-giant star in the constellation of Grus.

Alnair visual magnitude is 1.74, making it the 30th brightest star in the sky. Thanks to its high brightness, Alnair is clearly visible when observed from locations with dark skyes, and should be also quite easily visible from light polluted areas.

The table below summarizes the key facts about Alnair:

Alnair - α Gruis (alpha Gruis) is below the horizon from Greenwich, United Kingdom edit_location_alt.

Celestial coordinates and finder chart of Alnair

Alnair is situated south of the celestial equator, as such, it is more easily visible from the southern hemisphere. Celestial coordinates for the J2000 equinox as well as galactic coordinates of Alnair are provided in the following table:

22h 08m 13s
-46° 57’ 39”

The simplified sky map below shows the position of Alnair in the sky:

Finder chart Alnair - α Gruis (alpha Gruis) star
Simplified finder chart for Alnair - α Gruis (alpha Gruis).

Visibility of Alnair from your location

Location: Greenwich, United Kingdom edit_location_alt
Latitude: 51° 28’ 47” N
Longitude: 0° 00’ 00” E
Timezone: Europe/London

Alnair - α Gruis (alpha Gruis) is currently not visible from Greenwich, United Kingdom edit_location_alt

Digitized Sky Survey image of Alnair

The image below is a photograph of Alnair from the Digitized Sky Survey 2 (DSS2 - see the credits section) taken in the red channel. The area of sky represented in the image is 0.5x0.5 degrees (30x30 arcmins). The proper motion of Alnair is 0.129 arcsec per year in Right Ascension and -0.151 arcsec per year in Declination and the associated displacement for the next 1000 years is represented with the red arrow.

Image of Alnair - α Gruis (alpha Gruis) star
DSS2 image of Alnair. The red arrow shows the motion of Alnair during the next 1000 years (2.15 arcmin in Right Ascension and -2.52 arcmin in declination);

Distance of Alnair from the Sun and relative movement

Alnair is distant 101.37 light years from the Sun and it is moving far from the Sun at the speed of 12 kilometers per second.

31.09 pc
101.37 ly
12 km/s
0.129 arcsec/year
-0.151 arcsec/year

Spectral properties of Alnair

Alnair belongs to spectral class B7 and has a luminosity class of IV corresponding to a sub-giant star.


The red dot in the diagram below shows where Alnair is situated in the Hertzsprung–Russell diagram.

HR Diagram
H-R diagram showing the position of Alnair. Attribution: Richard Powell / CC BY-SA

Alnair star system properties

Alnair is a visual double star which can be observed only with the help of very large telescopes. The table below shows key information about the Alnair double sysyem:

28.4 arcsec

Alternative designations of Alnair

α Gruis
(alpha Gruis)
Gl 848.2