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: 6:46  
clear_day Transit: 12:51  
SunsetSet: 18:55 south
sunny DaytimeWhat's Visible Now
All Constellations » Orion » 

τ Orionis (tau Orionis)

Altitude: 0.7°   Azimuth: 258.1°   Direction: West-South-West

τ Orionis is a multiple giant star in the constellation of Orion.

τ Orionis visual magnitude is 3.6. Because of its moderate brightness, τ Orionis should be easily visible from locations with dark skyes, while it can be barely visible, or not visible at all, from skyes affected by light pollution.

The table below summarizes the key facts about τ Orionis:


τ Orionis (tau Orionis) is above the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: 0.7°
Azimuth: 258.1°
Direction: West-South-West

Celestial coordinates and finder chart of τ Orionis

τ 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 τ Orionis are provided in the following table:

05h 17m 36s
-06° 50’ 39”

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

Finder chart τ Orionis (tau Orionis) star
Simplified finder chart for τ Orionis (tau Orionis).

Visibility of τ 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 τ Orionis (tau 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: 96.8°
Max altitude: 31.7°
Azimuth: 263.2°

Digitized Sky Survey image of τ Orionis

The image below is a photograph of τ 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 τ Orionis is -0.015 arcsec per year in Right Ascension and -0.008 arcsec per year in Declination and the associated displacement for the next 10000 years is represented with the red arrow.

Image of τ Orionis (tau Orionis) star
DSS2 image of τ Orionis. The red arrow shows the motion of τ Orionis during the next 10000 years (-2.50 arcmin in Right Ascension and -1.33 arcmin in declination);

Distance of τ Orionis from the Sun and relative movement

τ Orionis is distant 554.42 light years from the Sun and it is moving far from the Sun at the speed of 20 kilometers per second.

170.07 pc
554.42 ly
20 km/s
-0.015 arcsec/year
-0.008 arcsec/year

Spectral properties of τ Orionis

τ Orionis belongs to spectral class B5 and has a luminosity class of III corresponding to a giant star.


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

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

τ Orionis star system properties

τ Orionis 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 τ Orionis double sysyem:

36 arcsec

Alternative designations of τ Orionis

τ Orionis
(tau Orionis)