Abbreviation: CMi

Genitive: Canis Minoris

English: The Lesser Dog

Size Ranking: 71st

Area: 380 square degrees

Fully visible: 89°N – 77°S.


This constellation while being quite diminutive, is of some importance in terrestrial navigation because it contains the eighth brightest star, hence is often used in astronomy as a ‘stepping stone’ when browsing the heavens.

Canis Minor represents the smaller of the two dogs of Orion, the hunter. Both Orion and Canis Major, which represents the larger dog, lie nearby.

Canis Minor is easily located by starting with a line joining Sirius, αCMa, and  Betelgeuse, αOri, and then forming an equilateral triangle where the third corner, at a similar altitude to Betelgeuse, will correspond with Procyon, αCMi.

Apart from its two brightest stars , Canis Minor contains little of note.


Features of Interest:

αCMi, named Procyon, is the eighth brightest star in the sky, at magnitude 0.4. The name Procyon is of Greek origin, meaning ‘before the dog’, from the fact that, in the Northern hemisphere, it rises before the other dog star, Sirius, αCMa. It is a white star, slightly less liminous than Sirius, and slightly further away, at 11.4ly. It shares with Sirius the peculiarity of having a white-dwarf partner, Procyon B, which is 10,000 times fainter than Procyon and orbits it every 41 years. The two appear so close, separation 5.2”, PA 021°, that only large professioal telescopes can separate them.

White-dwarfs are stars at the end of their lives and are very hot, very small and very dense. Sirius B is estimated to have the mass of the Sun packed into a sphere less than 1% of the Sun’s diameter. Its resulting density is 100,000 times that of water.

βCMi, named Gomeisa, is a blue-white main– sequence star, 170ly away and of magnitude 2.9.


1. Redshift 2 – Mares Multimedia

2. The Guinness Book of Astronomy – Patrick Moore

3. Stars and Planets – Ian Ridpath and Wil Tirion

4. Sky Charts – Cartes du Ciel V 2.75.

5. Where the Stars Are – Orion..