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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: 7:45  
clear_day Transit: 11:48  
SunsetSet: 15:51 south
sleep NighttimeWhat's Visible Now?
All Constellations » Orion » 

θ1 Orionis (theta1 Orionis)

Altitude: 4.8°   Azimuth: 104.8°   Direction: East-South-East

θ1 Orionis is a variable and multiple hypergiant star in the constellation of Orion.

θ1 Orionis visual magnitude is 6.7. Because of its reltive faintness, θ1 Orionis should be visible only from locations with dark skyes, while it is not visible at all from skyes affected by light pollution.

The table below summarizes the key facts about θ1 Orionis:


θ1 Orionis (theta1 Orionis) is above the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: 4.8°
Azimuth: 104.8°
Direction: East-South-East

Celestial coordinates and finder chart of θ1 Orionis

θ1 Orionis 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 θ1 Orionis are provided in the following table:

05h 35m 17s
-05° 23’ 16”

The simplified sky map below shows the position of θ1 Orionis in the sky:

Finder chart θ1 Orionis (theta1 Orionis) star
Simplified finder chart for θ1 Orionis (theta1 Orionis).

Visibility of θ1 Orionis 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 θ1 Orionis (theta1 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: 95.4°
Max altitude: 33.1°
Azimuth: 264.6°

Digitized Sky Survey image of θ1 Orionis

The image below is a photograph of θ1 Orionis 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 θ1 Orionis is 0.005 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 θ1 Orionis (theta1 Orionis) star
DSS2 image of θ1 Orionis. The red arrow shows the motion of θ1 Orionis during the next 100000 years (8.33 arcmin in Right Ascension and 3.33 arcmin in declination);

Distance of θ1 Orionis from the Sun and relative movement

θ1 Orionis is distant 32,600,000.00 light years from the Sun and it is moving far from the Sun at the speed of 31 kilometers per second.

10,000,000.00 pc
32,600,000.00 ly
31 km/s
0.005 arcsec/year
0.002 arcsec/year

Spectral properties of θ1 Orionis

θ1 Orionis belongs to spectral class B0 and has a luminosity class of V corresponding to a hypergiant star.


The red dot in the diagram below shows where θ1 Orionis is situated in the Hertzsprung–Russell diagram.

HR Diagram
H-R diagram showing the position of θ1 Orionis. Attribution: Richard Powell / CC BY-SA

θ1 Orionis star system properties

θ1 Orionis is a visual double star which can be observed with binoculars or small telescopes. The table below shows key information about the θ1 Orionis double sysyem:

117 arcsec

Alternative designations of θ1 Orionis

θ1 Orionis
(theta1 Orionis)