Gemini

Authors: Susanne M Hoffmann, Youla Azkarrula, Doris Vickers

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

One of the 88 IAU constellations.

Etymology and History

The Greek constellation ...

Origin of Constellation

Greco-Roman

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

These stars many astronomers have called Castor and Pollux. They say that of all brothers they were the most affectionate, not striving in rivalry for the leadership, nor acting without previous consultation. As a reward for their services of friendship, Jupiter is thought to have put them in the sky as well-known stars. Neptune, with like intention, has rewarded them for he gave them horses to ride, and power to aid shipwrecked men.

Others have called them Hercules and Apollo; some, even Triptolemus, whom we mentioned before, and Iasion, beloved of Ceres — both carried to the stars.

Those who speak of Castor and Pollux add this information, that Castor was slain in the town of Aphidnae, at the time when the Lacedemonians were fighting the Athenians. Others say that when Lynceus and Idas were attacking Sparta, he perished there. Homer states that Pollux granted to his brother one half of his life, so that they shine on alternate days. (Mary Ward 1960)

Almagest Δίδυμοι

id	Greek (Heiberg 1898)	English (Toomer 1984)	ident.
	Διδύμων ἀστερισμός
1	ὁ ἐπὶ τῆς κεφαλῆς τοῦ ἠγουμένου Διδύμου	The star an the head of the advance twin	alf Gem
2	ὁ ἐπὶ τῆς κεφαλῆς τοῦ ἐπομένου Διδύμου ὑπόκιρρος.	The reddish star on the head of the rear twin	bet Gem
3	ὁ ἐν τῷ ἀριστερῷ πήχει τοῦ ἠγουμένου Διδύμου.	Thc star in the lcft forearm of the advance twin	tet Gem
4	ὁ ἐν τῷ αὐτῷ βραχύουι.	Thc star in the same [left] upper arm	tau Gem
5	ὁ ἐπόμενος αὐτῷ καὶ κατὰ τοῦ μεταφρένου.	The one to the rear of that, just over the place between the shoulders	iot Gem
6	ὁ τούτῳ ἑπόμενος ἐπὶ τοῦ δεξιοῦ ὤμου τοῦ αὐτοῦ Διδύμου,	The one to the rear of this, an the right shoulder ofthe same [ advance] twin	ups Gem
	ὁ ἐπὶ τοῦ ἐπομένου ὤμου τοῦ ἐπομένου Διδύμου	The star on the rear shouldcr of the rear twin	kap Gem
	ὁ ἐπὶ τοῦ δεξιοῦ πλευροῦ τοῦ προηγουμένου Διδύμου.	The star on the right side of the advance twin	57 Gem
	ὁ ἐπὶ τοῦ ἀριστεροῦ πλευροῦ τοῦ ἐπομένου Διδύμου.	The star on the left side of the rear twin	58 Gem
	ὁ ἐπὶ τοῦ ἀριστεροῦ γόνατος τοῦ ἠγουμένου Διδύμου.	The star on the left knee of the advance twin	eps Gem
	ὁ ὑπὸ τὸ ἀριστερὸν γόνυ τοῦ ἐπομένου Διδύμου.	The star under the left knee of the rear twin	zet Gem
	ὁ ἐν τῷ ἀριστερῷ βουβῶνι τοῦ ἐπομένου Διδύμου.	The star in the left groin of the rear twin	del Gem
	ὁ ὑπὲρ τὴν δεξιὰν ἀγκύλην τοῦ αὐτοῦ Διδύμου.	The star over the bend in the right knee of the same [rear] twin	lam Gem
	ὁ ὑπὲρ τὴν δεξιὰν ἀγκύλην τοῦ αὐτοῦ Διδύμου.	The star on the forward foot of the advance twin	eta Gem
	ὁ τούτῳ ἐπόμενος ἐπὶ τοῦ αὐτοῦ ποδός.	The one to the rear of this on the same foot	mu Gem
	ὁ ἐπὶ τοῦ δεξιοῦ ἀκρόποδος τοῦ ἠγουμένου Διδύμου.	The star on the right foot of the advance twin	nu Gem
	ὁ ἐπὶ τοῦ ἀριστεροῦ ἀκρόποδος τοῦ ἐπομένου Διδύμου.	The star on the left foot of the rear twin	gam Gem
	ὁ ἐπὶ τοῦ δεξιοῦ ἀκρόποδος τοῦ ἐπομένου Διδύμου.	The star an the right foot of the rear twin	xi Gem
	ἀστέρες τη, ὥν β’ μεγέθους β, γ’ ἓ, δ’ ὅ, ε’ β.
	Οἱ περὶ τοὺς Διδύμους ἀμόρφωτοι.	Stars araund Gemini outside the constellation:
	ὁ προηγούμενος τοῦ πρόποδος τοῦ ἠγουμένου Διδύμου	The star in advance of the forward foot of the advance twin	1 Gem
	ὁ προηγούμενος τοῦ ἠγουμένου γόνατος λαμπρός	The bright star in advance of the advance knee.	kap Aur
	ὁ προηγούμενος τοῦ ἀριστεροῦ γόνατος τοῦ ἐπομένοου Διδύμου.	The star in advance of the left knee of the rear twin	36 Gem
	τῶν ἐπομένων τῇ δεξιᾷ χειρὶ τοῦ ἐπομένου Διδύμου, τριῶν ἐπ’ εὐθείας ὁ βόρειος.	The northernmost of the three stars in a straight line to the rear of the right arm of the rear twin	85 Gem
	ὁ μέσος τῶν τριῶν.	The middle one of the three	81 Gem
	ὁ νότιος αὐτῶν καὶ πρὸς τῷ πήχει τῆς χειρός!	The southernmost of them, near the forearm of the [right] arm	74 Gem
	ὁ ἐπόμενος τοῦς προειρημένοις γ’ λαμπρός!	The bright star to the rear of the above-mentioned 3	zet Gem
	ἀστέρες ξ, ὧν δ’ μεγέθους ἢ, ε' δ.	(7 stars, 3 of the fourth magnitude, 4-of the fifth}

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

Stars within the Constellation Area

id	Label	IAU design.	description	Vmag
1	Pollux	HIP 37826	Constellation lines	1.14
2	Castor	HIP 36850	Constellation lines	1.58
3	-	HIP 36850A	Inside the hull	1.9
4	Alhena	HIP 31681	Constellation lines	1.92
5	Tejat	HIP 30343	Constellation lines	2.87
6	Mebsuta	HIP 32246	Constellation lines	2.98
7	-	HIP 36850B	Inside the hull	3
8	Propus	HIP 29655	Constellation lines (Vertex)	3.28
9	Alzirr	HIP 32362	Constellation lines (Vertex)	3.36
10	Wasat	HIP 35550	Constellation lines	3.53
11	λ Geminorum	HIP 35350	Constellation lines (Vertex)	3.559
12	κ Geminorum	HIP 37740	Constellation lines (Vertex)	3.57
13	θ Geminorum	HIP 33018	Constellation lines (Vertex)	3.6
14	ι Geminorum	HIP 36046	Constellation lines	3.79
15	Mekbuda	HIP 34088	Constellation lines	3.79
16	υ Geminorum	HIP 36962	Constellation lines	4.06
17	ν Geminorum	HIP 30883	Constellation lines	4.14
18	ρ Geminorum	HIP 36366	Inside the hull	4.18
19	σ Geminorum	HIP 37629	Constellation lines	4.29
20	τ Geminorum	HIP 34693	Constellation lines	4.42
21	51 Gem	HIP 34909	Inside the hull	5
22	65 Gem	HIP 36429	Inside the hull	5.01
23	57 Gem	HIP 35846	Inside the hull	5.022
24	64 Gem	HIP 36393	Inside the hull	5.064
25	56 Gem	HIP 35699	Inside the hull	5.08
26	ω Geminorum	HIP 33927	Inside the hull	5.181
27	26 Gem	HIP 32104	Inside the hull	5.21
28	63 Gem	HIP 36238	Inside the hull	5.24
29	36 Gem	HIP 32921	Inside the hull	5.259
30	49 Aur	HIP 31434	Inside the hull	5.26
31	76 Gem	HIP 37704	Inside the hull	5.289
32	-	HIP 36896	Constellation lines	5.347
33	28 Gem	HIP 32311	Inside the hull	5.44
34	45 Gem	HIP 34440	Inside the hull	5.476
35	-	HIP 32968	Inside the hull	5.671
36	41 Gem	HIP 33715	Inside the hull	5.69
37	IS Gem	HIP 32740	Inside the hull	5.708
38	53 Gem	HIP 35152	Inside the hull	5.71
39	53 Aur	HIP 31737	Inside the hull	5.744
40	37 Gem	HIP 33277	Inside the hull	5.748
41	-	HIP 33914	Inside the hull	5.75
42	47 Gem	HIP 34722	Inside the hull	5.75
43	59 Gem	HIP 35941	Inside the hull	5.759
44	52 Gem	HIP 35025	Inside the hull	5.82
45	-	HIP 33937	Inside the hull	5.848
46	48 Gem	HIP 34819	Inside the hull	5.85
47	33 Gem	HIP 32753	Inside the hull	5.87
48	-	HIP 33421	Inside the hull	5.927
49	61 Gem	HIP 36156	Inside the hull	5.935
50	NP Gem	HIP 33929	Inside the hull	5.94
51	44 Gem	HIP 34182	Inside the hull	6.01
52	-	HIP 30570	Inside the hull	6.05
53	-	HIP 31813	Inside the hull	6.08
54	-	HIP 37339	Constellation lines	6.165
55	58 Gem	HIP 35842	Inside the hull	6.17
56	-	HIP 37269	Inside the hull	6.18
57	-	HIP 33595	Inside the hull	6.19
58	-	HIP 35345	Inside the hull	6.196
59	16 Gem	HIP 30769	Inside the hull	6.22
60	* 54 Aur A	HIP 31852	Inside the hull	6.22
61	20 Gem	HIP 31158	Inside the hull	6.242
62	-	HIP 32020	Inside the hull	6.272
63	-	HIP 30501	Inside the hull	6.345
64	-	HIP 36325	Inside the hull	6.36
65	-	HIP 37165	Inside the hull	6.37
66	-	HIP 32539	Inside the hull	6.37
67	-	HIP 31850	Inside the hull	6.38
68	-	HIP 35253	Inside the hull	6.389
69	40 Gem	HIP 33650	Inside the hull	6.397
70	-	HIP 34608	Inside the hull	6.42
71	25 Gem	HIP 32019	Inside the hull	6.427
72	-	HIP 34367	Inside the hull	6.464
73	-	HIP 31650	Inside the hull	6.48
74	-	HIP 32431	Inside the hull	6.49
75	-	HIP 34763	Inside the hull	6.5
76	-	HIP 36152	Inside the hull	6.52
77	-	HIP 37179	Constellation lines (Vertex)	6.85
78	-	HIP 38228	Constellation lines (Vertex)	6.91
79	-	HIP 38363	Constellation lines (Vertex)	7

Transfer and Transformation of the Constellation

• 
  Gemini in Fortin's Atlas Céleste, 3rd edition (1795).

References

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