Canis Major (Latin for big dog) is one of the 88 modern constellations, and was also in Ptolemy's list of 48 constellations. It is said to represent one of the dogs following Orion the hunter (see also the constellations of Orion, Canis Minor, and Canes Venatici.) Canis Major contains Sirius, the brightest star in the night sky, and that star is part of the Winter Triangle.

Notable features

Canis Major's alpha star Sirius is the brightest star besides the Sun as seen from Earth. It is also one of the nearest. The star is referred to as the Dog Star; its name Sirius means scorching.

Other named stars in Canis Major (all names from Arabic):

• Murzim (β Canis Majoris)
• Muliphen (γ Canis Majoris)
• Wezen (δ Canis Majoris)
• Adara (ε Canis Majoris)
• Furud (ζ Canis Majoris)
• Aludra (η Canis Majoris)

Notable deep sky objects

There aren't many bright deep sky objects in this region of sky. The only Messier object in Canis Major is M41 (NGC 2287), an open cluster of visual magnitude 4.6. It is located about 4 degrees directly south of Sirius.

Canis Major Dwarf is a recently-discovered dwarf galaxy orbiting the Milky Way, in the constellation.

Mythology

This constellation was known to the easterners from the time immemorial. In early European classical days, this constellation represented Laelaps, Acteon 's hound; or sometimes the hound of Procris, Diana's nymph; or the one given by Aurora to Cephalus, so famed for its speed that Zeus elevated it to the sky. Most commonly, Canis Major (or perhaps just the star Sirius) is Orion's hunting dog, pursuing Lepus the hare or helping Orion fight Taurus the bull, and is referred to in this way by Aratos , Homer and Hesiod. The ancient Greeks refer only to one dog, but by Roman times, Canis Minor appears as Orion's second dog.

Roman myth also refers to Canis Major as Custos Europae, the dog guarding Europa but failing to prevent her abduction by Jupiter in the form of a bull; and as Janitor Lethaeus, the watchdog of Hell.

Depending on the faintness of stars considered, Canis Major resembles a dog facing either above or below the ecliptic. When facing below, since Sirius was considered a dog in its own right, early greek mythology sometimes considered it to be two headed. As such, together with the area of the sky that is deserted (now considered as the new and extremely faint constellations Camelopardalis and Lynx), and the other features of the area in the Zodiac sign of Gemini (i.e. the Milky Way, and the constellations Gemini, Orion, Auriga, and Canis Major), this may be the origin of the myth of the cattle of Geryon, which forms one of The Twelve Labours of Herakles.