Definition: A constellation is a group of stars and Canis Major is a constellation that looks a little bit like a big dog, hence its name. There is a similar but smaller constellation called Canis Minor (small dog), which can be found above Canis Major in the night sky. To find the constellation Canis Major, first find the three bright stars that make up Orion’s belt and trace a diagonal line downwards in the sky, until you come to the bright star, Sirius, the brightest in the constellation of Canis Major.