Winter Triangle. Optical image of the Winter Triangle of bright stars in the constellations Orion, the hunter, Canis Minor, the little dog, and Canis Major, the great dog. North is at top. The stars form an equilateral triangle and are, clockwise from upper left, Procyon (Alpha Canis Minoris) in Canis Minor, Betelgeuse (Alpha Orionis, orange) in Orion and Sirius (Alpha Canis Majoris) in Canis Major. Sirius is the brightest star in the sky. The Milky Way is seen running vertically through the Winter Triangle. The faint constellation Monoceros, the unicorn, takes up most of the area within the triangle.