Canis Major – the Big Dog Constellation

Jun 23, 2022

~7 min

Topics:Constellations & Asterisms Skywatching Stars

What is special about Canis Major constellation? It is one of the easiest to find, featuring the brightest star in our entire sky. Learn when and how to observe it.

Learn how to easily find famous star patterns and constellations in the night sky. Discover interesting facts about each of the constellations.

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Facts about Canis Major constellation

Name: Canis Major (the Greater Dog)
Abbreviation: CMa
Size: 380 sq. deg.
Right ascension: 7 h
Declination: −20°
Visible between: 60°N – 90°S
Celestial hemisphere: Southern
Brightest star: Sirius (Alpha Canis Majoris)
Main stars: 15
Messier DSO: 1
Bordering constellations: Monoceros, Lepus, Columba, Puppis

Canis Major location

Canis Major belongs to the southern celestial hemisphere and is visible at latitudes between 60°N and 90°S. Observers from the Southern Hemisphere can see it between November and April. In the Northern Hemisphere, the constellation appears from December to March and rises so low above the horizon that the southern part of it is barely visible.

Where is Canis Major in the sky?

Canis Major is next to its master, the hunter Orion. Along with Canis Minor, Lepus, and Monoceros, they belong to the Orion family of constellations. They represent a hunting scene: Orion and his dogs are chasing down the hare while the unicorn is prancing by.

How to find Canis Major in the sky?

To locate Canis Major, look for the Orion’s Belt asterism. It will serve as a waymark to Sirius, the brightest star in the constellation that marks the dog’s neck. You might need binoculars to spot the rest of the stars that form a stick figure dog.

In the northern latitudes, the constellation appears low above the horizon. If you observe the sky from the Northern Hemisphere, draw an imaginary line through the three stars of the Orion’s Belt. Stretch the line down, and slightly to its left, you’ll find Sirius. Below and to its left, you might see Adhara and Wezen, marking the hips and the hind paws of the dog. These two stars form a nearly-equilateral triangle with Aludra, which is located to their left and represents the dog’s tail. To the right of Sirius, you may find Murzim, which is the front paws, and to the left – Muliphen, which is the eye.
In the Southern Hemisphere, constellations appear rotated 180 degrees: upside-down and left-right reversed, so Orion is below Canis Major. The imaginary line through the three stars of the Orion’s Belt should point upwards – Sirius will be in this direction. The dog’s hind legs – Wezen and Adhara – will be above its head. The dog’s tail, Aludra, will be located to their right. Murzim (the front paws) will be to the left of Sirius, and Muliphen (the eye) will be to the right.

How to find Canis Major with stargazing apps?

The easiest way to find Canis Major is to use stargazing apps. This way, you will certainly not be mistaken and identify all the stars correctly. We’ll explain how to find the constellation using the Star Walk 2 and Sky Tonight apps.

Star Walk 2:

Launch the app and tap the magnifier icon in the lower-left corner of the screen;
Type “Canis Major” in the search bar;
Tap the corresponding search result;
You’ll see the constellation’s current position in the sky;
Point your device at the sky and follow the white arrow to find the constellation.

Sky Tonight:

Launch the app and tap the magnifier icon at the lower part of the screen;
Type “Canis Major” in the search bar;
Find the constellation name that will appear in the search results;
Tap on the target icon opposite the name;
You’ll see the constellation’s current position in the sky;
Point your device at the sky and follow the white arrow to find the constellation.

Canis Major stars

You can form the Great Dog’s figure in the sky in different ways, using from 8 to 16 stars. Most of the patterns feature the most known stars in the constellation: Sirius, Adhara, Wezen, Murzim (Mirzam), Aludra, Phurud, and Muliphen (Muliphein). Let’s take a look at the top-3 brightest stars in Canis Major.

Sirius – Alpha Canis Majoris

Sirius (α CMa, HR 2491, HIP 32349), which means “scorching” or “glowing” in Greek, is the brightest star (right after the Sun) and the 7th brightest celestial body (magnitude -1.46). In fact, it is not a single star but a binary star system composed of Sirius A, the biggest and the brightest of the two stars, and Sirius B, which is known as “the Pup”.

Sirius is called “the Dog star” since it is on the collar of the celestial dog. But this is not the only way it is connected with dogs. For Greeks and Romans, Sirius, rising right before the Sun in the summer sky, also marked the Dog Days – the period when it is unbearably hot outside, and only dogs are mad enough to walk outdoors.

Adhara – Epsilon Canis Majoris

Like Sirius, Adhara (ε CMa, HR 2618, HIP 33579) is also a binary star system. Its name means “maidens” in Arabic. It is the second brightest star in Canis Major. But there were times when Adhara was the brightest in the entire sky (it was 4.7 million years ago, so you are unlikely to have seen that). Although it has faded since then, it is still the brightest ultraviolet light source in our sky. Its apparent magnitude is 1.5.

Wezen – Delta Canis Majoris

Wezen (δ CMa, HR 2693, HIP 34444) is a yellow-white supergiant star with a magnitude of 1.8. Its name comes from the Arabic word for “weight”. The star is “heavy” indeed: it barely rises above the horizon in the Northern Hemisphere. Besides, Wezen is 17 times more massive than the Sun. In 100,000 years, it will become a red supergiant and, consequently, a supernova.

Deep-sky objects in Canis Major

Canis Major has 45 deep-sky objects, one of them belonging to the Messier list.

Messier 41 (M41) - Little Beehive Cluster

The Little Beehive Cluster (Messier 41, M41, NGC 2287) is the only Messier object in the Canis Major constellation. It is an open cluster that contains about 100 stars. It has an apparent magnitude of 4.5, which is acceptable even for the unaided eye, but of course, binoculars will improve the view. Find the cluster below Sirius in the area where the dog’s heart would be.

PGC 5065047 - Canis Major Dwarf Galaxy

The Canis Major Dwarf overdensity (CMa Dwarf, PGC 5065047) is classified as an irregular galaxy pulled apart by the Milky Way’s gravitational field. It contains about a billion stars, mostly red giants. The Canis Major Dwarf Galaxy is considered our closest neighbor: it is located 25,000 light-years away from the Solar System and 42,000 light-years away from the Milky Way’s center. However, it is difficult to observe because the dust and gas near the plane of the Milky Way obscure it.

NGC 2359 - Thor's Helmet

Thor’s Helmet (NGC 2359, the Duck Nebula) is an emission nebula that resembles the shape of the winged helmet worn by the Norse god of thunder. It is ten times larger than the Solar System and is 12,000 light-years away from us. Thor’s Helmet is too far to be seen through binoculars, but big telescope owners might find it above the dog’s head. It is also a popular object for astrophotography.

Canis Major mythology

Canis Major in Greek mythology

According to the Greek myth, Canis Major represents Laelaps – the magic dog that could hunt down and catch any prey. The myth says the dog had changed several owners and eventually was sent after the Teumessian fox – a magic animal that could never be caught. Zeus realized that the hunt would be never-ending and turned them to stone. Then, in one version, he placed both animals in the sky, the dog as Canis Major and the fox as Canis Minor. Another version says the dog was the only one immortalized in the stars. The Greeks also considered Canis Major and Canis Minor as the two dogs belonging to the hunter Orion.

Canis Major in other cultures

People of different cultures associated the stars in the Canis Major constellation with different characters and symbols. The Romans believed Canis Major was the dog that was guarding Europa but failed to stop Jupiter from abducting her. Mesopotamian people viewed the constellation not as a dog but as an arrow and a bow. Chinese astronomers classified the Canis Major’s stars as a group of asterisms: The Military Market, The Wild Cockerel, The Bow and Arrow, and The Celestial Wolf. In ancient Egypt people paid special attention to its one particular star, Sirius: its appearance in the dawn sky in June would herald the flooding of the Nile, which marked the beginning of the year.

F.A.Q.

When was Canis Major discovered?

In 150 A.D., the Greek scientist Ptolemy published The Almagest – a book in which 48 constellations discovered by Greek astronomers were described. Canis Major was listed among them. The Mesopotamians mentioned its stars even earlier – Sirius and the southern stars of Canis Major were described in tablets that date back to 1100 B.C.

How far is Canis Major from the Earth?

It’s difficult to give a definite answer because the stars united in one constellation can be at different distances from the Earth. For example, there are 8.6 light-years between the Earth and Sirius and 430.5 light-years between the Earth and Adhara, which is next in brightness.

What is the best month to see Canis Major?

For observers from the Southern Hemisphere, the constellation is visible between November and April. It appears in the Northern Hemisphere from December to March, reaching its maximum height above the horizon in February.

Are Sirius and Canis Major the same?

No. Canis Major is a constellation, and Sirius is its brightest star. You’ll learn the special features of the constellations and will never confuse them with the stars after passing our quiz!

What’s the largest constellation in the sky? Which constellation contains a W-shaped asterism? Take this quiz to test your knowledge about constellations!

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Is Sirius the North Star?

No, Sirius and the North Star (Polaris) are two different stars, both being the brightest in their constellations (the North Star is located in Ursa Minor). Sirius is also the most luminous star in the entire sky.

Now you know all you need about Canis Major. You've learned the story behind its name, the ways to find it in the sky, and the best time to observe it. Share the knowledge with your friends via messengers or social media. We wish you clear skies and happy observations!

Text Credit:Vito Technology, Inc.