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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: 7:52  
clear_day Transit: 11:51  
SunsetSet: 15:49 south
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All Constellations » Canis Major » 

τ Canis Majoris (tau Canis Majoris)

Altitude: 2.9°   Azimuth: 222.2°   Direction: South-West

τ Canis Majoris is a variable and multiple supergiant star in the constellation of Canis Major.

τ Canis Majoris visual magnitude is 4.4. Because of its moderate brightness, τ Canis Majoris 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 Canis Majoris:


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

Altitude: 2.9°
Azimuth: 222.2°
Direction: South-West

Celestial coordinates and finder chart of τ Canis Majoris

τ Canis Majoris 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 Canis Majoris are provided in the following table:

07h 18m 42s
-24° 57’ 15”
Canis Major

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

Finder chart τ Canis Majoris (tau Canis Majoris) star
Simplified finder chart for τ Canis Majoris (tau Canis Majoris).

Visibility of τ Canis Majoris 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 Canis Majoris (tau Canis Majoris) 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: 115.0°
Max altitude: 13.6°
Azimuth: 245.0°

Digitized Sky Survey image of τ Canis Majoris

The image below is a photograph of τ Canis Majoris 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 Canis Majoris is -0.009 arcsec per year in Right Ascension and 0.01 arcsec per year in Declination and the associated displacement for the next 10000 years is represented with the red arrow.

Image of τ Canis Majoris (tau Canis Majoris) star
DSS2 image of τ Canis Majoris. The red arrow shows the motion of τ Canis Majoris during the next 10000 years (-1.50 arcmin in Right Ascension and 1.67 arcmin in declination);

Distance of τ Canis Majoris from the Sun and relative movement

τ Canis Majoris is distant 3,196.08 light years from the Sun and it is moving far from the Sun at the speed of 40 kilometers per second.

980.39 pc
3,196.08 ly
40 km/s
-0.009 arcsec/year
0.01 arcsec/year

Spectral properties of τ Canis Majoris

τ Canis Majoris belongs to spectral class O9 and has a luminosity class of I corresponding to a supergiant star.


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

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

Alternative designations of τ Canis Majoris

τ Canis Majoris
(tau Canis Majoris)
30 Canis Majoris