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A Complete Guide to the Solar System and the Night Sky
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public Observing fromLocation: Greenwich, United Kingdom edit_location_alt
north SunriseRise: 7:37  
clear_day Transit: 11:46  
SunsetSet: 15:55 south
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All Constellations » Gemini » 

Alhena - γ Geminorum (gamma Geminorum)

Altitude: -21.0°   Azimuth: 345.4°   Direction: North-North-West

Alhena, also designated as γ Geminorum (gamma Geminorum), is a multiple hypergiant star in the constellation of Gemini.

Alhena visual magnitude is 1.93, making it the 42th brightest star in the sky. Thanks to its high brightness, Alhena 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 Alhena:


Alhena - γ Geminorum (gamma Geminorum) is below the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: -21.0°
Azimuth: 345.4°
Direction: North-North-West

Celestial coordinates and finder chart of Alhena

Alhena is situated close to the celestial equator, as such, it is at least partly visible from both hemispheres in certain times of the year. Celestial coordinates for the J2000 equinox as well as galactic coordinates of Alhena are provided in the following table:

06h 37m 42s
+16° 23’ 57”

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

Finder chart Alhena - γ Geminorum (gamma Geminorum) star
Simplified finder chart for Alhena - γ Geminorum (gamma Geminorum).

Visibility of Alhena from your location

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

Today's Alhena - γ Geminorum (gamma Geminorum) rise, transit and set times from Greenwich, United Kingdom edit_location_alt are the following (all times relative to the local timezone Europe/London):

Azimuth: 73.6°
Max altitude: 54.9°
Azimuth: 286.4°

Digitized Sky Survey image of Alhena

The image below is a photograph of Alhena 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 Alhena is 0.042 arcsec per year in Right Ascension and -0.042 arcsec per year in Declination and the associated displacement for the next 10000 years is represented with the red arrow.

Image of Alhena - γ Geminorum (gamma Geminorum) star
DSS2 image of Alhena. The red arrow shows the motion of Alhena during the next 10000 years (7.00 arcmin in Right Ascension and -7.00 arcmin in declination);

Distance of Alhena from the Sun and relative movement

Alhena is distant 104.76 light years from the Sun and it is moving towards the Sun at the speed of 13 kilometers per second.

32.13 pc
104.76 ly
-13 km/s
0.042 arcsec/year
-0.042 arcsec/year

Spectral properties of Alhena

Alhena belongs to spectral class A0 and has a luminosity class of IV corresponding to a hypergiant star.


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

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

Alhena star system properties

Alhena 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 Alhena double sysyem:

143.5 arcsec

Alternative designations of Alhena

γ Geminorum
(gamma Geminorum)
24 Geminorum