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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: 7:48  
clear_day Transit: 11:49  
SunsetSet: 15:50 south
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All Constellations » Orion » 

Alnilam - ε Orionis (epsilon Orionis)

Altitude: -37.4°   Azimuth: 23.1°   Direction: North-North-East

Alnilam, also designated as ε Orionis (epsilon Orionis), is a variable and double hypergiant star in the constellation of Orion.

Alnilam visual magnitude is 1.7, making it the 28th brightest star in the sky. Thanks to its high brightness, Alnilam 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 Alnilam:


Alnilam - ε Orionis (epsilon Orionis) is below the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: -37.4°
Azimuth: 23.1°
Direction: North-North-East

Celestial coordinates and finder chart of Alnilam

Alnilam 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 Alnilam are provided in the following table:

05h 36m 12s
-01° 12’ 06”

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

Finder chart Alnilam - ε Orionis (epsilon Orionis) star
Simplified finder chart for Alnilam - ε Orionis (epsilon Orionis).

Visibility of Alnilam 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 Alnilam - ε Orionis (epsilon Orionis) 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: 91.2°
Max altitude: 37.3°
Azimuth: 268.8°

Digitized Sky Survey image of Alnilam

The image below is a photograph of Alnilam 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 Alnilam is 0.001 arcsec per year in Right Ascension and -0.002 arcsec per year in Declination and the associated displacement for the next 100000 years is represented with the red arrow.

Image of Alnilam - ε Orionis (epsilon Orionis) star
DSS2 image of Alnilam. The red arrow shows the motion of Alnilam during the next 100000 years (1.67 arcmin in Right Ascension and -3.33 arcmin in declination);

Distance of Alnilam from the Sun and relative movement

Alnilam is distant 1,341.56 light years from the Sun and it is moving far from the Sun at the speed of 26 kilometers per second.

411.52 pc
1,341.56 ly
26 km/s
0.001 arcsec/year
-0.002 arcsec/year

Spectral properties of Alnilam

Alnilam belongs to spectral class B0 and has a luminosity class of I corresponding to a hypergiant star.


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

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

Alnilam star system properties

Alnilam 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 Alnilam double sysyem:

179.9 arcsec

Alternative designations of Alnilam

ε Orionis
(epsilon Orionis)