Canis Major

Authors: Susanne M Hoffmann, Youla Azkarrula, Doris Vickers

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CMa star chart (IAU and Sky & Telescope magazine, Roger Sinnott & Rick Fienberg)

One of the 88 IAU constellations. This is the (one and only) constellation of the Dog in ancient Greek astronomy.

Orion-Group of constellations on the Kugel Globe, drawing and animated GIF by SMH 2025.

Etymology and History

Origin of Constellation

In Hellenistic times, Greek astronomy had only one constellation, the Dog, so there was no need to distinguish between a large and a small dog. According to Eratosthenes, this dog had the bright star Sirius on its tongue. Ptolemy in Roman times placed it on the dog's snout.

What is interesting about Sirius, however, is that today we use the Greek proper name from Hellenistic times. Ptolemy in Roman times called the brightest star of the constellation ‘the Dog’.

Bright Star

Sirius is the brightest star in the night sky and therefore particularly easy to observe at dusk. This makes it ideal for a special calendar function. In the course of the year, it does not matter where the beginning and end are – the only important thing is that the stellar year, like the solar year, has approximately 365 days. There were therefore several possibilities in different cultures as to when to celebrate the New Year: in Mesopotamia, it was usually the spring equinox, but there was also the variant with the autumn equinox. In Egypt, the New Year was celebrated in summer – with five days ‘between the years’ when it was hardly possible to work anyway due to the intense heat. This ancient Egyptian custom was still known when the country on the Nile was under Greek and Roman rule. This explains the ancient term ‘dog days’ for the hottest days of the year with the heliacal rising of Sirius.

The Greek word for the star – seirios, scorching – can refer both to its brightness and to the heat of summer at the time of its heliacal rising. The latter was certainly the case with the Egyptian word: since the 3rd millennium, the word ‘Sothis’ has been used to refer to a constellation of at least three stars, which later – perhaps only in the 1st millennium – was restricted to the bright Sirius. As in Mesopotamia, the Sothis star system was used in Egypt to determine the calendar. However, whether the rising of Sirius was really associated with the flooding of the Nile is highly controversial among researchers and difficult to prove. What is certain is that the star system was associated with the goddess of magic, Isis. She was always one of the supreme deities in the Egyptian pantheon, and in Roman times, the growing Christianity had to assert itself against the cult of Isis, among others, as an extremely strong competitor.

In the case of Sirius, however, it is interesting that we now use the Greek proper name from the Hellenistic period. Ptolemy in Roman times called the brightest star in the constellation ‘the dog’. Many astronomers were puzzled by the question of why Ptolemy described the star as reddish. This even sparked speculation about a possible supernova or nova on its companion, a white dwarf. Both can be dismissed because it may be a matter of uncertainty in text translations: Eratosthenes already described the star as ‘fiery’ and “flaming” or ‘flickering’. The flickering and shimmering in all colours is caused by the Earth's atmosphere. In most cultures, reddish stars are referred to as fire stars: e.g. Antares in China or Aldebaran in Mesopotamia. In the case of Sirius, the word probably means ‘glittering’ in the sense of ‘bright compared to other stars’. It would therefore be a metaphor for great brightness, like a beacon in the dark, heralding the new year and the hot season. The attribution of ‘red’ would therefore be a misunderstanding in one of the numerous stages of translation. Sirius is and was white in colour even back then. This is confirmed by other ancient astronomers and astrologers in their descriptions, e.g. Manilius in the first century.

Babylonian

Babylonian astronomy records the constellation Arrow (KAK.SI.SA₂) in this region of the sky. There are probably two constellations in this region of the sky: the Arrow and the Bow. In some versions of Babylonian uranography, they are held by a person, presumably a deity, standing east of the Milky Way. However, this does not seem to apply to all variants; in MUL.APIN, for example, no such figure is mentioned, but rather two independent constellations (Bow and Arrow), while textual descriptions from the 1st millennium suggest such a figure.

Sirius definitely belongs to the Arrow and, as the brightest star, sometimes stands alone for this constellation, especially when observed at twilight (i.e. for calendar determination). Therefore, there are various suggestions in research as to which stars other than Sirius also belong to the arrow. A line from Sirius to Procyon is rather unlikely from a calendar perspective. Presumably, the constellation of Sirius should be thought of as southward. Since the constellation of the bow should be located near the arrow, it is presumed to be in the southernmost stars of the dog or in the faint stars east of it. Whether it is a bow and arrow, just an arrow or a deity with an arrow (and bow), there is certainly no dog to be found here in Babylonian mythology: the Babylonian constellation Dog belongs to the goddess of medicine, Gula, and is located in the area of our constellation Hercules.

Greco-Roman

Aratos

[326] Such is also his guardian Dog, seen standing on its two legs below the soaring back of Orion, variegated, not bright overall, but dark in the region of the belly as it moves round; but the tip of its [330] jaw is inset with a formidable star, that blazes most intensely: and so men call it the Scorcher. When Sirius rises with the sun, trees can no longer outwit it by feebly putting forth leaves. For with its keen shafts it easily pierces their ranks, [335] and strengthens some, but destroys all the growth of others. We also hear of it at its setting. The other stars lying round about Sirius define the legs more faintly. (Kidd 1997)

Hipparchus

Rising (Lib II Cap V §10)

The Rising of ...

	east		south
	lam1	lam2	lam1	lam2
star
duration	2 1/8 hours = 127.5 min = 31 7/8 degree

Setting (Lib II Cap VI §10)

	west		south
	lam1	lam2	lam1	lam2
star
duration	2 2/3 hours = 160 min = 40°

Stars Mentioned

	Greek	German	English	ident.	src		lam_culm
					Lib II Cap V §10	rising, east, first
					Lib II Cap V §10	rising, east, last
					Lib II Cap VI §2	setting CrB, south, last	Psc 13.5
					Lib II Cap VI §13	setting Aql, south, first	Ari 2
					Lib III Cap I §9	rising Ori, south, last	Psc 13

Hyginus, Astronomica

He is said to have been given by Jove as a guardian for Europa, and later to have come to Minos. When Minos was ill, Procris, wife of Cephalus, is said to have cured him, and received the dog as a reward for her services, as she was very fond of hunting and the dog was so swift that no beast could escape. After her death the dog came to Cephalus her husband, who brought it to Thebes with him when he came. There was a fox there which was said to be so swift that it could outrun all dogs. So when the two animals met, Jupiter, in a dilemma, as Istros says, changed them both to stone.

Some have said that this is the dog of Orion, and because Orion was devoted to hunting, the dog was put with him among the stars. Others have called it the dog of Icarus. These many suggestions have their own advocates.

The Dog has one star on his tongue which itself is called Dog, and on its head another which Isis is thought to have put there under her own name, and to have called it Sirius on account of the brilliance of the flame because it seems to shine more than the rest. So, in order for men to recognize it more easily, she called it Sirius. (Mary Ward 1960)

Almagest Κύων

id	Greek (Heiberg 1898)	English (Toomer 1984)	ident.
	Κυνὸς ἀστερισμός	Constellation of the Dog
1	ἐν τῷ στόματι λαμπρότατος καλούμενος Κύωυ καὶ ὑπόκιρρος.	The star in the mouth, the brightest, which is called 'the Dog' and is reddish	alf CMa
2	ὁ ἐπὶ τῶν ὡτοη.	The star on the ears	tet CMa
3	ὁ ἐπὶ τῆς κεφαλῆ	The star on the head	gam CMa
4	τῶν ἐκ τῷ τραχήλῳ β ὁ βόρειος	The northernrriost of the 2 stars in the neck	iot CMa
5	ὁ φόσιος αὐτῶν	The southernmost of them	pi CMa
6	ὁ ἐπὶ τοῦ στήθους.	The star on the chest	nu3 CMa
7	τῶν ἐπὶ τοῦ δεξιοῦ γόνατος β ὁ βόρειος.	The northernmost of the 2 stars on the right knee	nu2 CMa
8	ὁ νοτιώτερος αὐτῶν.	The southernmost of them	bet CMa
9	ὁ ἐπ’ ἄκρῳ τῷ ἐμπροσθίῳ ποδί	The star on the end of the front leg	xi1 CMa
10	τῶν ἐν τῷ ἀριστερῷ γόνατι β ὁ προηγούμευος.	The more advanced of the 2 stars in the left knee	xi2 CMa
11	ὁ ὁ ἐπόμενος αὐτῶν	The rearmost of them	omi2 CMa
12	τῶν ἐν τῷ ἀριστερῷ ὤμῳ β’ ὁ ἑπόμενος;	The rearmost of the 2 stars in the left shoulder	omi1 CMa
13	ὁ προηγούμενος αὐτῶν	The more advanced of them	del CMa
14	ὁ ἐν τῇ ἐκφύσει τοῦ ἀριστεροῦ μηροῦ.	The star in the place where the 1eft thigh joins [the body)	del CMa
15	ὁ ὑπὸ τὴν κοιλίαν ἐν τοῦς μεσομήροις	The star below the belly, in the middle of the thighs	eps CMa
16	ὁ ἐπὶ τῆς ἀγκύλης τοῦ δεξιοῦ ποδός	The star on the joint of the right leg	kap CMa
17	ὁ ἐπ’ ἄκρου τοῦ δεξιοῦ ποδός.	The star on the end of the right leg	zet CMa
18	ὁ ἐπὶ τῆς οὐρᾶς	The star on the tail	eta CMa
	ἀστέρες τῆ, ὥν αἱ μεγέθους ἂ, γ’ ἓ, δ’ ἓ, ε’ ξ.	{18 stars, 1 of the first magnitude, 5 of the third, 5 ofthe fourth, 7 of the fifth}
	Οἱ περὶ τὸν Κύνα ἀμόρφωτοι.
19	ὁ ἀπ’ ἄρκτου τῆς κορυφῆς τοῦ Κυνός.	The star to the north of the top of The Dog	22 Mon
20	τῶν ὑπὸ τοὺς ὀπισθίους πόδας ὡς ἐπ’ εὐθείας ὁ ὁ νοτιώτατος.	The southernmost ofthe 4 stars almost on a straight line under the hind legs	θ Col
21	ὁ τούτου βορειότερος.	The one north of this	κ Col
22	ὁ ἔτι τούτου βορειότερος.	The one north again of this	δ Col
23	ὁ λοιπὸς καὶ βορειότερος τῶν δ	The last and northernmost of the 4	λ CMa
24	τῶν πρὸς δυσμὰς τοῦς τέσσαρσιη ὡς ἐπ’ εὐθείας γ ὁ προἠγούμενος	The most advanced ofthe 3 stars almost on a straightline to the west of the [ above] four	μ Col
25	ὁ μέσος αὐτῶν	The middle one	λ Col
26	ὁ ἑπόμευος τῶν τριῶν.	The rearmost of the three	γ Col
27	τῶν ὑπὸ τούτους β λαμπρῶν ὁ ἐπόμευος.	The rearmost of thc 2 bright stars under these	β Col
28	ὁ προηγούμενος αὐτῶν.	The more advanccd of them	α Col
29	ὁ λοιπὸς καὶ νοτιώτερος τῶν προειρημένων.	The last star, to the south of the abovc	ε Col
all	ἀστέρες ἱα, ὥν β’ μεγέθους β, δ’ 9.	{11 stars, 2 of the second magnitude, 9 of the fourth)

Convex Hull for the stars inside Kyon (CC BY Youla Azkarrula).

Stars within the Constellation Area

id	Label	IAU design.	description	Vmag
1	Sirius	HIP 32349	Constellation lines	-1.46
2	NAME CMa Dwarf Galaxy	NAME CMa Dwarf Galaxy	Inside the hull	-0.1
3	Adhara	HIP 33579	Constellation lines	1.5
4	Wezen	HIP 34444	Constellation lines	1.84
5	Mirzam	HIP 30324	Constellation lines (Vertex)	1.97
6	Aludra	HIP 35904	Constellation lines (Vertex)	2.45
7	Cl Collinder 121	Cl Collinder 121	Inside the hull	2.6
8	Furud	HIP 30122	Constellation lines (Vertex)	2.99
9	ο 2 Canis Majoris	HIP 33977	Constellation lines	3.02
10	Nganurganity	HIP 33856	Constellation lines	3.47
11	ω Canis Majoris	HIP 35037	Constellation lines	3.82
12	ο 1 Canis Majoris	HIP 33152	Constellation lines	3.87
13	κ Canis Majoris	HIP 32759	Constellation lines (Vertex)	3.89
14	ν 2 Canis Majoris	HIP 31592	Constellation lines	3.91
15	θ Canis Majoris	HIP 33160	Constellation lines (Vertex)	4.08
16	Muliphein	HIP 34045	Constellation lines (Vertex)	4.12
17	ξ 1 Canis Majoris	HIP 31125	Constellation lines	4.33
18	ι Canis Majoris	HIP 33347	Constellation lines	4.385
19	τ Canis Majoris	HIP 35415	Constellation lines (Vertex)	4.4
20	ν 3 Canis Majoris	HIP 31700	Constellation lines	4.43
21	ξ 2 Canis Majoris	HIP 31416	Constellation lines	4.5
22	M 41	M 41	Inside the hull	4.5
23	-	HIP 35205	Inside the hull	4.64
24	27 CMa	HIP 34981	Inside the hull	4.65
25	π Canis Majoris	HIP 33302	Constellation lines	4.664
26	15 CMa	HIP 33092	Constellation lines	4.83
27	μ Canis Majoris	HIP 33345	Constellation lines	5.09
28	10 CMa	HIP 32292	Inside the hull	5.17
29	11 CMa	HIP 32492	Constellation lines	5.272
30	-	HIP 35427	Inside the hull	5.288
31	-	HIP 32411	Inside the hull	5.298
32	-	HIP 33316	Inside the hull	5.3
33	-	HIP 34624	Inside the hull	5.448
34	-	HIP 33478	Inside the hull	5.47
35	-	HIP 32677	Inside the hull	5.51
36	-	HIP 35044	Inside the hull	5.582
37	-	HIP 33575	Inside the hull	5.583
38	-	HR 2522	Inside the hull	5.59
39	-	HIP 30436	Inside the hull	5.6
40	LS CMa	HIP 33804	Inside the hull	5.635
41	-	HIP 33077	Constellation lines	5.648
42	-	HIP 32385	Inside the hull	5.68
43	LZ CMa	HIP 34579	Inside the hull	5.69
44	ν 1 Canis Majoris	HIP 31564	Inside the hull	5.695
45	-	HIP 31870	Constellation lines	5.71
46	-	HIP 32810	Inside the hull	5.747
47	-	HIP 30836	Inside the hull	5.761
48	-	HIP 32809	Inside the hull	5.771
49	17 CMa	HIP 33248	Constellation lines	5.792
50	-	HIP 34758	Inside the hull	5.825
51	FV CMa	HIP 34360	Inside the hull	5.83
52	26 CMa	HIP 34798	Inside the hull	5.897
53	-	HIP 31037	Inside the hull	5.903
54	-	HIP 32366	Inside the hull	5.916
55	-	HIP 34914	Inside the hull	5.96
56	-	HIP 35611	Inside the hull	5.986
57	-	HIP 31758	Inside the hull	6.03
58	-	HIP 32368	Inside the hull	6.033
59	-	HIP 29843	Constellation lines (Vertex)	6.04
60	-	HIP 33094	Inside the hull	6.04
61	-	HIP 31859	Inside the hull	6.05
62	-	HIP 30711	Inside the hull	6.07
63	-	HIP 34142	Inside the hull	6.072
64	12 CMa	HIP 32504	Inside the hull	6.08
65	-	HIP 34318	Inside the hull	6.088
66	GY CMa	HIP 34924	Inside the hull	6.101
67	-	HIP 33079	Inside the hull	6.123
68	-	HIP 33126	Inside the hull	6.22
69	-	HIP 32144	Inside the hull	6.23
70	-	HIP 33492	Inside the hull	6.23
71	-	HIP 33666	Inside the hull	6.26
72	-	HIP 30062	Inside the hull	6.27
73	-	HIP 34940	Inside the hull	6.27
74	-	HIP 33760	Inside the hull	6.279
75	-	HIP 33703	Inside the hull	6.305
76	-	HIP 32827	Inside the hull	6.314
77	-	HIP 31469	Inside the hull	6.32
78	-	HIP 34248	Inside the hull	6.325
79	-	HIP 33330	Inside the hull	6.34
80	-	HIP 35132	Inside the hull	6.34
81	-	HIP 33532	Inside the hull	6.361
82	-	HIP 30503	Inside the hull	6.39
83	-	HIP 33591	Inside the hull	6.395
84	-	HIP 31266	Inside the hull	6.402
85	V415 CMa	HIP 31593	Inside the hull	6.41
86	-	HIP 32322	Inside the hull	6.43
87	-	HIP 35326	Inside the hull	6.434
88	-	HIP 30988	Inside the hull	6.44
89	KX CMa	HIP 33040	Inside the hull	6.44
90	-	HIP 30141	Inside the hull	6.48
91	-	HIP 31736	Inside the hull	6.5
92	NGC 2354	NGC 2354	Inside the hull	6.5

Transfer and Transformation of the Constellation

• 
  Canis Major and Canis Minor on the Kugel Globe (1st c.BCE), drawing by SMH 2021.
• 
  Canis Major on the Mainz Globe following Orion (drawing by SMH 2021)
• 
  Canis Major on Mercator (1551)
• 
  Canis Major in Bayer's Uranometria (1603)
• 
  Canis Major in Hevelius (1690)
• 
  Canis Major in Flamsteed/ Fortin (1776)
• 
  Canis Major in Jamieson (1822)
• 
  Canis Major in Hall (1825)

Mythology

Eratosthenes recounts two stories about how the dog might have come to be in the sky: on the one hand, he could be Orion's faithful companion, and on the other, he could have been a gift to Princess Europa.

As Orion's dog, he accompanied him on the hunt and is considered a faithful companion and helper to humans against wild animals. That is why he was immortalised in the starry sky with Orion's ascent, writes Eratosthenes.

However, the dog could also have had a whole series of other owners: together with the javelin, it is said to have been given by Zeus to the king's daughter Europa as her guardian. She later passed these gifts on to her son Minos. As king of Crete, he later suffered from an illness from which the Attic princess Prokris cured him. Out of gratitude, he gave her the immortal dog and the accurate javelin. When Prokris married King Cephalus of Thebes, the gifts came into his possession. Thebes was plagued by an uncatchable fox, and when they hunted it with the swift dog, only Zeus could end the pursuit: He turned the fox to stone and placed the dog among the stars.

Hyginus and Ovid see the two dogs as the faithful companions of Ikarios, the bringer of culture, who, at the behest of the god Dionysus, introduced the art of viticulture and wine production to the land around Athens.

References

• References (general)
• References (Babylonian)
• References (ancient Greco-Roman)
• References (medieval)