Located in the southern celestial hemisphere, Canis Major is a constellation visible in the summer for the southern hemisphere and winter for the northern hemisphere sky. The constellation was included in Ptolemy’s 2nd century constellations. The name Canis Major is Latin for “greater dog” in contrast to Canis Minor, the “lesser dog”; both figures are commonly represented as following the constellation of Orion the hunter through the sky.

Covering 380 square degrees or 0.921% of the sky, Canis Major ranks 43rd of the 88 modern constellations in regards to size. The Milky Way passes through Canis Major and several open clusters lie within its borders, which includes M41. Sirius can be found here, and the brightest star in the night sky, which is known as the “dog star”. It is bright because of its proximity to the solar system, which is in contrast to the other bright stars of the constellation. The other bright stars are of greater distance from the solar system and have a higher luminosity.

	Applicable Information
Visibility In Pacific Northwest	October to March
Best Times To View	February
Right Ascension	06h 12.5m to 07h 27.5m
Declination	−11.03° to −33.25°
Area	380 square degrees
Main Stars	8
Brightest Object	Sirius
Meteor showers	0
Messier objects	1
Neighboring Constellations	Monoceros, Lepus, Columba, Puppis

Mythology

In ancient Mesopotamia, Sirius was seen as an arrow aiming towards Orion, while the southern stars of Canis Major, which date to around 1100 BC. The Ancient Greeks replaced the bow and arrow depiction with that of a dog.

In Greek Mythology, Canis Major represented the dog Laelaps, a gift from Zeus to Europa; or sometimes the hound of Procris, Diana’s nymph; or the one given by Aurora to Cephalus. Canis Major was also considered to represent one of Orion’s hunting dogs, which were pursuing Lepus the Hare or helping Orion fight Taurus the Bull; and is referred to in this way by Aratos, Homer and Hesiod. By Roman times, Canis Minor appears as Orion’s second dog.

The Roman myth refers to Canis Major as Custos Europae, the dog guarding Europa but it failed to prevent her abduction by Jupiter.

In medieval Arab astronomy, the constellation became al-Kalb al-Akbar, “the Greater Dog.”

In Chinese astronomy, the modern constellation of Canis Major is located in the Vermilion Bird.

Both the Māori and the Tuamotus recognized the figure of Canis Major as a distinct entity; however, the constellation was sometimes part of other constellations.

Stars

Canis Major is a prominent constellation because of its many bright stars, including Sirius, which is the brightest star in the night sky, and 3 additional stars above magnitude 2.0. 

German cartographer Johann Bayer used the Greek letters Alpha through Omicron to label the most prominent stars in the constellation. It would take subsequent observers time to observe the southern part of the constellation that were hard to discern from Central Europe. Johann Elert Bode would later add the stars designated Sigma, Tau and Omega. John Flamsteed numbered 31 stars.

Sirius is the brightest star in the night sky, with its name coming from the Greek word for “scorching” or “searing”. Sirius is also a binary star; its companion Sirius B is a white dwarf that is 10,000 times fainter. The two stars orbit each other every 50 years. Sirius was the basis for the ancient Egyptian calendar.

The band of the Milky Way goes through Canis Major. The only Messier object in Canis Major is M41, otherwise known as NGC 2287, which is an open cluster that covers an area the apparent size of the full moon.

NGC 2362 is a small, compact open cluster that contains roughly 60 stars. It covers nearly 12 light years in diameter that appears huddled around Tau when seen through binoculars.

NGC 2354 a faint open cluster, with around 15 stars that are visible with binoculars. NGC 2359, otherwise known as Thor’s Helmet or the Duck Nebula, is a relatively bright emission nebula in Canis Major.

Make sure to check out other articles on the site, including a brief introduction to constellations, other constellation articles, and more!