Gemini constellation
Latin Gemini, genitive Geminorum, abbreviation Gem
North up, east to the left, as you see the sky. The lines are a common figure; the stars are from the catalogue.
The myth
Castor and Pollux, twin brothers: Castor mortal, Pollux immortal as a son of Zeus. When Castor fell, Pollux shared his immortality with him; since then they stand together in the sky. Their heads are the two bright stars side by side. Sailors held them as patrons. In December the Geminid meteors come from their direction.
When can Gemini be seen?
It stands highest around 10 pm in February. It can be seen from everywhere north of 57°S, and it never sets north of 77°N.
The brightest stars
| Star | Designation | Magnitude | Colour |
|---|---|---|---|
| Pollux | β Gem | 1.14 | orange |
| Alhena | γ Gem | 1.93 | white |
| Castor | α Gem | 1.98 | white |
| Tejat | μ Gem | 2.88 | reddish |
| – | α Gem | 2.88 | white |
| Mebsuta | ε Gem | 2.98 | reddish |
| Propus | η Gem | 3.28 | reddish |
| Alzirr | ξ Gem | 3.36 | yellowish white |
The smaller the number, the brighter: below 1 are the brightest stars of the sky, 4 is hard to see under a city sky. Greek letters after Johann Bayer (1603).
Constellation and zodiac sign
The constellation Gemini and the zodiac sign of the same name are not the same. The signs divide the Sun's path into twelve equal parts of 30 degrees, counted from the vernal equinox; the constellations differ in size, and because the Earth's axis slowly wobbles, they now lie almost one sign further on.
Meteors
The Geminids radiate from Gemini: when they fall and how to see them.