Canis Major (Latin: Big Dog) is located south east of Orion, and is a southern hemisphere constellation seen from both northern latitudes (winter time) and southern latitudes (summer time) between November and April. Canis Major represents the giant Orion’s chief hunting dog, Laelaps, who could catch any prey it pursued, with the brightest star in the sky Sirius (mag -1.46) depicting the dog’s nose. The constellation is also part of the Orion family of constellations which shows the huntsman (Orion) his two dogs (Canis Major, Canis Minor) and a unicorn (Monoceros) pursuing a small hare (Lepus) through the night sky.
The constellation has roots in many cultures, but the Greek myth is the best known of these ancient stories. To the Greeks, the group of stars represented the dog Laelaps, who was a gift to Europa from Zeus. In other myths, the dog is the faithful hound of Orion the Hunter, chasing Lepus the Hare across the sky on their nightly hunts, while to other Laelaps is seen as helping Orion fight a giant bull represented by the nearby constellation Taurus. By Roman times, Laelaps is one of two dogs following the great hunter (the other being Canis Minor), and to them the dog is the protector of Europa, although Jupiter disguised as a bull still managed to abduct the celebrated princess after which the continent of Europe is named.
Sirius A is the fifth nearest star to our own sun (8.6 light-years away) and appears blue white in color, although it might be called a rainbow star as it often flickers with many different hues, leading to a multitude of mistaken UFO reports in the past. Interestingly, the “dog star” is actually a binary system, with the second star Sirius B (The Pup) being a white dwarf that orbits the dominant star, but to the naked eye the two stars cannot be distinguished. In ancient times, Sirius rising near the same time as the sun (heliacal rising) represented the beginning of the Egyptian year, marked by the flooding of the Nile river. The period from 20 days before and after this occurrence was referred to as the “dog days” as ancients thought that the heat of the “dog star” was added to that of the sun to create the summer’s hottest temperatures.
Adhara is the second brightest star in the constellation and represents one of the dog’s legs. This is also a binary star system around 430 light years from Earth, and actually emits more than a thousand times more light than Sirius, such that if it were placed at the same distance as Sirius, it would appear around 200 times brighter than the “dog star”.
The star Wezen marks Canis Major’s hindquarter, and is a 10 million year old yellow-white super giant star located 1,800 light years distant. Murzim, a blue white giant, is a star located 500 light years from our sun, with a name that translates from Arabic into ‘the herald.’ Audla is located 3,000 light years distant, and is a blue supergiant variable star that dwarfs our sun in comparison. Tau Canis Major is an eclipsing binary star almost 3,200 light years away from our own home world. Phurud Canis Majoris, is anther star located in the constellation, and it shares the sky with the other lesser star known as Gamma Canis Majoris.
Deep Field Object
If you are looking for objects other than the magnificent stars in the constellation, there are several deep space object that will captivate the attention of any serious astronomer for hours on end. With the right viewing tools, one can see some of the most amazing objects in the night sky. This include Messier 41, an open cluster containing around 100 stars located 2,300 light years away, as well as the small emission nebula NGC 2359, known affectionately as Thor’s Helmet, found over 15,000 light years away and formed around an extremely hot star which is thought to be in its pre-supernova stage.
The constellation also contains the Canis Major Dwarf Galaxy, which was discovered in the year 2003, and contains about a billion stars. It is also now believed to be the closest galaxy to the Milky Way, being a mere 42,000 light years from our galactic center, and just 25,000 light years from our own solar system. This rare wonder is difficult to see, however, because it lies behind the Milky Way’s plane of sight. There are also two spiral galaxies, NGC 2207 and IC 2163, which are currently colliding around 130 million light-years away from Earth.
Do yourself a favor, and check this classic constellation out during your next outing to view the wonders of our heavens. The mythology of the constellation may draw us in, but the sights that can be found in the group of stars is nothing short of amazing.