| GEMINI Chart | Midnight Culmination | Skylore | Description | Asterisms |
| Special Stars | Star Clusters | Discussed in these Shows |

Constellation Data

  • Name: GEMINI
  • Translation: Twins
  • Abbreviation: Gem
  • Genitive: Geminorum
  • Size: 30
  • Regions: Zodiac
  • RA: 7 hours
  • Decl: +25 degrees
  • Season: Winter
  • Midnight Culmination: January 5
  • Pages where GEMINI is discussed in Chet Raymo's 365 Starry Nights: 3,25,31-34,40,45

What is the Genitive form?
What is Right Ascension (RA)?
Is this constellation ever visible from my latitude? What is Declination?

Where should I look for a constellation on a date before or after its midnight culmination? What is Midnight Culmination?


To the Greeks, Castor and Pollux were the twin sons of Zeus and the mortal woman Leda. Homer's Iliad tells how the beauty of their sister Helen "launched a thousand ships" in the Trojan war. After Castor's death, Pollux was overwhelmed with grief, and wanted to share his immortality with his twin. Finally Zeus reunited them by placing them together in the heavens. With the oath "By Jiminy," sailors revered the Gemini twins as the Protectors of ships.

The Geminids meteor shower, around October 19.


Look for the two bright stars, Castor and Pollux, which form one vertex of the Winter Hexagon. Castor is closer to Capella, in Auriga on the north; and Pollus is closer to Procyon, in Canis Minor on the south. Cancer and Leo.htm">Leo lie to the east.

[star chart]

Star chart created with Voyager II Software for Macintosh, published by Carina Software. This is just a taste of what Voyager can do! For info on Voyager II software, call Carina Software at (510) 355-1266, write them at 12919 Alcosta Blvd Suite #7, San Ramon, CA 94583, or visit Carina Software's home page and check out Voyager II for yourself.


Winter Hexagon (see Taurus).

What is an Asterism?

Special Stars

The two bright stars Castor and Pollux together form one vertex of the Winter Hexagon. Castor, on the Capella side, is actually six stars in one, ceaselessly revolving around one another in an intricately-choreographed cosmic dance. Pollux is the nearer of the twins, about 35 light years from the sun. Castor lies at a distance of 45 light years, and is a little less bright than Pollux.

Table of 25 Brightest Stars.
What is apparent stellar magnitude?

Star Clusters

M35 (Galactic cluster), mag. 5.6.

What are Star Clusters?

Discussed in these Shows

[Small Logo] ©1997 Welcome to the Basic Celestial Phenomena web site. To provide explanations of basic observational astronomy to students, teachers, families, and visitors to planetariums these pages have been written by an ex-OBU Planetarium Director, Kerry Magruder; the OBU Natural Sciences Coordinator, Mike Keas; and some of the students who work in the OBU planetarium.

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