Cetus

Authors: Susanne M Hoffmann, Youla Azkarrula, Doris Vickers, IanRidpath

---

star chart of Cetus by IAU and Sky & Telescope magazine (Roger Sinnott & Rick Fienberg)

One of the 88 IAU constellations. It is related to the group of constellations around the constellation Andromeda and highly likely originates from the Mediterranean coast, definitely not from Mesopotamia (as this region was covered by the constellation SIM.MAH). There is a comprehensive paper on this constellation. The Greek constellation probably originates from the east coast of the Mediterranean as the mythology of this seamonster either includes it in the tale of princess Andromeda threatened by a seamoster and rescued by the hero Perseus, or princess Hesione exposed to another seamonster and rescued by Hercules. The Andromeda saga is related to a rock in the ancient habour of Old Jaffa (Tel Aviv) while Hesione is a princess of Troy (Anatolia). In both cases, the seamonster is home to the Mediterranean.

Etymology and History

The Greek name κῆτος (ketos) does not in any case refer to a real animal, but only to a mythological creature. Its Latinized version "cetus", however, may also designate a whale. "Though archaeological findings of whale remains are uncommon in Greece, there exist few examples of ancient whalebones in the Aegean Sea, probably originating from stranded whales. ... Combined with archaeological artifacts as the bones of prehistorical giant sea creatures in the Wādī al-Ḥītān (Valley of Whales) in today's Egypt, this might have triggered traveller's imagination and have led to further stories (and cock-and-bull story)."

Origin of Constellation

As this constellation does not have a Babylonian equivalent, we suspect that it was taken from another culture in order to diversify the sky culture in Alexander's new empire.

Ketos (Cetus) is one of the classical Greek constellations: it belongs to the Andromeda group, which dates back to a tragedy by Sophocles (5th century BCE). In English texts from earlier centuries, the word was often mistakenly translated as ‘whale’. Apart from the fact that whales are not fish, Ketos is neither a whale nor a fish: it is the name of a sea monster, a terrifying mythical creature – it is best to leave the word untranslated, as with the names Cassiopeia, Andromeda and Cepheus.

The depiction on the Farnese Globe shows a dragon-like animal with a monstrous head with a kind of hump and a protruding tongue. It has a snake-like, coiled tail with a fish-like tail fin at the end. The creature has front legs with fins and claws. So it is definitely not a real animal.

Greek uranography ends below Ketos, i.e. there are no more constellations south of it because there are no more bright stars visible in the Mediterranean region. East of this area of the sky, too, there are only faint stars in a wide arc – there is a void of stars all the way to the Milky Way in Orion. From a few faint stars between Ketos and Orion, which do not form a distinctive pattern, a unimaginative chain of stars was formed, which was called ‘river’ (Eridanus). On the Farnese Globe, Ketos holds its front legs in this river. The tail fin touches the spout of Aquarius, and above the dorsal fin is the band of the little fish.

Most likely, the poet Aratos meant this combination of water currents around Ketos when he wrote about the stars under Ketos' tail fin and up to the spout of Aquarius, ‘all of which are called water’. On the Farnese Globe, it looks as if the sculptor understood the winding water lines as the shores of a large star ocean in which Ketos romps. In Ptolemy, it is the monster's chest rather than its front legs that shares a star with the river: the concept that Ketos represents this connection between these waters seems to have become canonical in antiquity.

The constellation has no Babylonian roots: according to MUL.APIN, the constellation of the giant swallow (SIM.MAḪ), or rather its head and wings, was located in its place (see the constellation Pisces).

It is interesting to note that Aratos, Eratosthenes and Ptolemy mention only two bright stars: α and β Ceti, which are visually 2.0 and 2.5 mag bright, respectively. The variable star Mira does not appear in any of the ancient star lists, although this star also sometimes reaches 2 mag. However, the star fluctuates in brightness between visible and invisible, so it is sometimes there and sometimes gone within its cycle of 332 days (approx. 11 months). It is disputed whether Hipparchus observed the star, as Hipparchus' original data has not been preserved. If the star was seen and recorded by an observer, this observation was no longer verifiable a few weeks later, so it was not noted in catalogues.

Greco-Roman

Aratus

Although she lies no small distance away, Andromeda is threatened by the approach of the great Sea-monster. [355] For in her course she lies exposed to the blast of the north wind from Thrace, while the southerly brings against her the hostile Monster, below the Ram and the two Fishes, and positioned a little above the starry River. For under the gods’ feet that too moves as a separate group, [360] a remnant of Eridanus, river of much weeping. It extends below the left foot of Orion. The tail-chains, by which the extremities of the Fishes are held, both come together as they descend from the tail-parts, and behind the Monster’s back-fin move jointly [365] as they converge, and terminate in a single star that lies close to the top of the Monster’s spine. (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

Whale. With regard to the Sea-Monster, they say that it was sent by Neptune to kill Andromeda, about whom we have already spoken. But because it was killed by Perseus, on account of its huge size and his valour it was placed amongst the constellations. (Mary Ward 1960)

Almagest Κῆτος

id	Greek (Heiberg 1898)	English (Toomer 1984)	ident.
	Κήτους ἀστερισμόρ
1	ὁ ἐπ’ ἄκρου τοῦ μυκτῆρος	The star on the tip of the nostrils	lam Cet
2	τῶν ἐν τῷ ῥύγχει ἢ ὁ ἑπόμενος ἐπ’ ἄκρας τῆς σιαγόνος	The three stars in the snout: the rearmost, on the end of the jaw	alf Cet
3	ὁ μέσος αὐτῶν καὶ ἐν μέσῳ τῷ στόματι	The three stars in the snout: the middle ane, in the middie of the mouth	gam Cet
4	ὁ προηγούμενος τῶν ν’ καὶ ἐπὶ τῆς γένυος	The three stars in the snout: the most advanced of the 3, on the cheek	del Cet
5	ὁ ἐπὶ τῆς ὀφρόος καὶ τοῦ ὀφθαλμοῦ	The star on the eyebrow and the eye	nu Cet
6	ὁ τούτου βορειότερος ὡς ἐπὶ τῆς τριχός	The one to the north of this, about on the hair	xi2 Cet
7	ὁ τούτων προηγούμευος ὡς ἐπὶ τῆς χαίτης	The one in advance of this, about on the mane	xi1 Cet
8	τοῦ ἐῃ τῷ στήθει τετραπλεύρου τῆς ἠγουμένης πλευρᾶς ὁ βόρειος	The quadrilateral in the chest: the northernmost star on thc advance side	rho Cet
9	ὁ νότιος τῆς ἠγουμένης πλευρᾶς	The quadrilateral in the chest: the southernmost one on the advance side	sig Cet
10	τῆς ἐπομένης πλευρᾶς ὁ βόρειος	The quadrilateral in the chest: the northernmost one on the rear side	eps Cet
11	ὁ νότιος τῆς ἐπομένης πλευρᾶς	The quadrilateral in the chest: the southernmost one on the rear side	pi Cet
12	τῶν ἐν τῷ σώματι ἢ’ ὁ μέσος	The midmost of the 3 stars in the body	tau Cet
13	ὁ νότιος αὐτῶν	The southernmost of them	ups Cet
14	ὁ βόρειος τῶν τριῶν	The northernmost of the three	zet Cet
15	τῶν πρὸς τῷ παρούρῳ β ὁ ἐπόμενος	The rearmost of the 2 stars by the section next to the tail	tet Cet
16	ὁ προηγούμευος αὐτῶν	The more advanced of them	eta Cet
17	τοῦ ἐν τῷ παρούρῳ τετραπλεύρου τῆς ἐπομένης πλευρᾶς ὁ βόρειος	The quadrilateral in the section next to the tail: the northernmost star on the rear side	phi2 Cet
18	ὁ νότιος τῆς ἐπομένης πλευρᾶς.	The quadrilateral in the section next to the tail: the southernmost one on thc rear side	HR 227
19	τῆς προηγουμένης πλευρᾶς ὁ βόρειος	The quadrilateral in the section next to the tail: the northernmost one on thc advance side	phi Cet
20	ὁ νότιος τῆς προηγουμένης πλευρᾶς	The quadrilateral in the section next to the tail: the southernmost one on the advance side	HR 190
21	τῶν ἐν ἄκροις τοῦς οὐραίοις ᾑ ὁ ἐπὶ τοῦ βορείου.	The 2 stars at the ends of the tail-fins: the one on the northern [tail-fin]	iot Cet
22	ὁ ἐπ’ ἄκρου τοῦ φοτίου οὐραέου	The 2 stars at the ends of the tail-fins: the one on the end of the southern tail-fin	bet Cet
	ἀστέρες πβ, ὥν γ’ μεγέδους ἰ, δ’ ἢ, εἱ δ.	{22 Stars, 10 of the third magnitude, 8 of the fourth, 4 of the fifth}

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

Stars within the Constellation Area

id	Label	IAU design.	description	Vmag
1	Diphda	HIP 3419	Constellation lines (Vertex)	2.01
2	Menkar	HIP 14135	Constellation lines (Vertex)	2.53
3	η Ceti	HIP 5364	Constellation lines	3.45
4	Kaffaljidhma	HIP 12706	Constellation lines	3.47
5	τ Ceti	HIP 8102	Inside the hull	3.5
6	ι Ceti	HIP 1562	Constellation lines (Vertex)	3.55
7	θ Ceti	HIP 6537	Constellation lines	3.59
8	Baten Kaitos	HIP 8645	Constellation lines	3.72
9	υ Ceti	HIP 9347	Constellation lines (Vertex)	4.02
10	δ Ceti	HIP 12387	Constellation lines	4.07
11	Alrescha A	HIP 9487	Inside the hull	4.11
12	π Ceti	HIP 12770	Constellation lines (Vertex)	4.236
13	ξ 2 Ceti	HIP 11484	Constellation lines	4.3
14	ξ 1 Ceti	HIP 10324	Constellation lines (Vertex)	4.35
15	ξ Piscium	HIP 8833	Inside the hull	4.604
16	χ Ceti	HIP 8497	Inside the hull	4.68
17	λ Ceti	HIP 13954	Constellation lines (Vertex)	4.7
18	σ Ceti	HIP 11783	Constellation lines	4.75
19	ϕ 1 Ceti	HIP 3455	Constellation lines	4.767
20	ρ Ceti	HIP 11345	Constellation lines	4.866
21	ϵ Ceti	HIP 12390	Constellation lines	4.87
22	ν Ceti	HIP 12093	Constellation lines	4.871
23	46 Cet	HIP 6670	Inside the hull	4.907
24	175 G. Cet	HIP 7999	Inside the hull	4.982
25	37 Cet	HIP 5799	Inside the hull	5.13
26	ϕ 2 Ceti	HIP 3909	Constellation lines	5.19
27	259 G. Cet	HIP 11738	Inside the hull	5.269
28	69 Cet	HIP 11021	Inside the hull	5.287
29	ϕ 3 Ceti	HIP 4371	Inside the hull	5.326
30	179 G. Cet	HIP 8230	Inside the hull	5.34
31	75 Cet	HIP 11791	Inside the hull	5.358
32	50 Cet	HIP 7450	Inside the hull	5.402
33	25 Cet	HIP 4914	Inside the hull	5.408
34	238 G. Cet	HIP 11029	Inside the hull	5.421
35	70 Cet	HIP 11046	Inside the hull	5.421
36	60 Cet	HIP 9589	Inside the hull	5.423
37	39 Cet	HIP 5951	Inside the hull	5.428
38	57 Cet	HIP 9326	Inside the hull	5.429
39	67 Cet	HIP 10642	Inside the hull	5.499
40	47 Cet	HIP 6748	Inside the hull	5.505
41	AR Cet	HIP 9372	Inside the hull	5.51
42	80 Cet	HIP 12107	Inside the hull	5.535
43	28 Cet	HIP 5164	Inside the hull	5.565
44	232 G. Cet	HIP 10723	Inside the hull	5.59
45	81 G. Cet	HIP 3849	Inside the hull	5.594
46	49 Cet	HIP 7345	Inside the hull	5.607
47	203 G. Cet	HIP 9622	Inside the hull	5.609
48	ϕ 4 Ceti	HIP 4587	Inside the hull	5.614
49	64 Cet	HIP 10212	Inside the hull	5.623
50	81 Cet	HIP 12247	Inside the hull	5.647
51	66 Cet	HIP 10305	Inside the hull	5.66
52	38 Cet	HIP 5833	Inside the hull	5.69
53	78 G. Cet	HIP 3717	Inside the hull	5.693
54	30 Cet	HIP 5296	Inside the hull	5.705
55	84 Cet	HIP 12530	Inside the hull	5.71
56	77 Cet	HIP 12002	Inside the hull	5.731
57	165 G. Cet	HIP 7276	Inside the hull	5.76
58	-	HIP 7916	Inside the hull	5.77
59	BK Cet	HIP 8778	Inside the hull	5.782
60	286 G. Cet	HIP 12444	Inside the hull	5.79
61	-	HIP 12114	Inside the hull	5.79
62	272 G. Cet	HIP 12148	Inside the hull	5.811
63	AB Cet	HIP 11348	Inside the hull	5.83
64	93 G. Cet	HIP 4346	Inside the hull	5.85
65	202 G. Cet	HIP 9572	Inside the hull	5.864
66	42 Cet	HIP 6226	Inside the hull	5.87
67	-	HIP 9353	Inside the hull	5.87
68	131 G. Psc	HIP 8404	Inside the hull	5.904
69	34 Cet	HIP 5594	Inside the hull	5.918
70	137 G. Cet	HIP 6564	Inside the hull	5.92
71	63 Cet	HIP 10234	Inside the hull	5.933
72	61 Cet	HIP 9631	Inside the hull	5.942
73	305 G. Cet	HIP 13679	Inside the hull	5.963
74	256 G. Cet	HIP 11687	Inside the hull	5.99
75	219 G. Cet	HIP 10215	Inside the hull	5.999
76	71 G. Cet	HIP 3436	Inside the hull	6.02
77	297 G. Cet	HIP 12862	Inside the hull	6.031
78	289 G. Cet	HIP 12584	Inside the hull	6.049
79	213 G. Cet	HIP 9999	Inside the hull	6.056
80	27 Cet	HIP 5121	Inside the hull	6.088
81	-	HR 492	Inside the hull	6.14
82	128 G. Cet	HIP 6272	Inside the hull	6.147
83	18 Cet	HIP 3559	Inside the hull	6.15
84	21 Cet	HIP 4257	Inside the hull	6.161
85	264 G. Cet	HIP 12022	Inside the hull	6.163
86	138 G. Cet	HIP 6605	Inside the hull	6.164
87	139 G. Cet	HIP 6589	Inside the hull	6.183
88	176 G. Cet	HIP 8094	Inside the hull	6.19
89	44 Cet	HIP 6539	Inside the hull	6.21
90	149 G. Cet	HIP 6822	Inside the hull	6.21
91	EH Cet	HIP 13756	Inside the hull	6.21
92	279 G. Cet	HIP 12318	Inside the hull	6.237
93	170 G. Cet	HIP 7580	Inside the hull	6.24
94	-	HIP 12318	Inside the hull	6.24
95	127 G. Cet	HIP 6283	Inside the hull	6.246
96	285 G. Cet	HIP 12447	Inside the hull	6.26
97	207 G. Cet	HIP 9827	Inside the hull	6.295
98	71 Cet	HIP 11261	Inside the hull	6.335
99	209 G. Cet	HIP 9862	Inside the hull	6.39
100	276 G. Cet	HIP 12272	Inside the hull	6.39
101	32 Cet	HIP 5485	Inside the hull	6.394
102	186 G. Cet	HIP 8664	Inside the hull	6.41
103	-	HIP 9094	Inside the hull	6.42
104	227 G. Cet	HIP 10396	Inside the hull	6.42
105	144 G. Cet	HIP 6717	Inside the hull	6.426
106	166 G. Cet	HIP 7362	Inside the hull	6.43
107	205 G. Cet	HIP 9655	Inside the hull	6.43
108	171 G. Cet	HIP 7597	Inside the hull	6.44
109	57 G. Cet	HIP 2846	Inside the hull	6.444
110	187 G. Cet	HIP 8688	Inside the hull	6.45
111	193 G. Cet	HIP 9237	Inside the hull	6.46
112	101 G. Cet	HIP 4801	Inside the hull	6.47
113	Mira	HIP 10826	Inside the hull	6.47
114	293 G. Cet	HIP 12720	Inside the hull	6.48
115	133 G. Cet	HIP 6427	Inside the hull	6.487
116	63 G. Cet	HIP 3175	Inside the hull	6.49
117	-	HIP 10233	Inside the hull	6.49
118	221 G. Cet	HIP 10273	Inside the hull	6.49
119	-	HIP 10854	Inside the hull	6.491
120	-	HR 206	Inside the hull	6.498
121	76 G. Cet	HIP 3576	Inside the hull	6.499
122	-	HIP 6687	Inside the hull	6.5
123	-	HIP 13482	Inside the hull	6.74

Transfer and Transformation of the Constellation

• 
  an apparent vessel for Cetus on the Kugel-Globe (drawing SMH 2024), 2nd or 1st century BCE
• 
  map of the Kugel Globe, Cetus in the center of two lines with rings, drawing by SMH 2024, 2nd or 1st century BCE
• 
  Some lines forming a stream of water in which Cetus is centered on the Farnese Globe (drawing by SMH 2021), 2nd or 1st century CE with Hellenistic predecessor
• 
  Figures of the Farnese Globe mapped to the Stellarium star chart (drawing and implementing by SMH 2021). Cetus-region.
• 
  map of the Mainz Globe with Cetus in the center, surrounded by many dots (star symbols), perhaps representing The Water (drawing by SMH 2023), 2nd century CE

• 
  Cetus at Planisferio celeste (Carlos Simón 1894)

Mythology

Greek

The monster was placed among the stars because it was a creature of Poseidon, god of the sea, and is intended to commemorate the glorious deed of Perseus. Since Andromeda was to be sacrificed to the monster, Perseus successfully fought the mythical creature and earned the gratitude of the beautiful princess, her parents and the country.

Weblinks

• Ridpath, Ian, “Star Tales: online edition”.

References

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