Gemini

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

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}

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)