Gemini
Gemini, the twins of the two brothers Castor and Pollux. Here are the most spectacular Geminid meteor shower and the myth of undying brotherly love.
Science
The scienceThe chief star Pollux is a red giant very close to the Sun (about 34 light-years away) and one of the nearest giant stars around which an exoplanet has been found. Seen through a telescope, Castor is a complex multiple system of six stars orbiting one another. In mid-December this constellation is the radiant of the "Geminid meteor shower," which peaks each year as the most dazzling shower of all.
Mythology
How it became a constellationThis is the story of two brothers, Castor and Polydeuces (Pollux), born to Zeus and the mortal queen Leda. Castor, being mortal, could not escape death, but Pollux, the son of a god, was immortal. When his brother fell in battle, Pollux could not bear his grief and begged to share his own immortality. Moved by the brothers' devotion, Zeus let them spend half of each day together in the heavens and half together in the underworld, then set them among the stars as an eternal symbol of brotherly love.
Observing Guide
how to observe🔭 How to find it
On a winter evening, look above Orion (to the northeast) and you'll see two stars of similar brightness side by side — the "brother stars" Castor and Pollux, marking the heads of the twins. Draw a diagonal from Rigel in Orion up through Betelgeuse and continue on to reach these two stars. From the two heads, two parallel rows of stars stretch back toward Orion to form the twins' bodies.
✨ What to look for
Near Castor's foot (toward Orion) lies the bright open cluster M35, a lovely spray of stars even in binoculars, with the far more distant and compact cluster NGC 2158 right beside it for contrast. Near Pollux sits the "Eskimo Nebula" (NGC 2392), a planetary nebula whose shell of gas resembles a face surrounded by a hood — a favorite target for small telescopes.
📍 Where to see it (US · Canada · UK · Australia)
From the US, Canada and UK, Gemini climbs high in the southern sky on winter evenings (December–February), Castor and Pollux passing almost overhead before the constellation tilts west and sets soon after dusk by late spring. From Australia the twins appear in the northern sky, upside down and only low-to-moderately high, during the southern summer (December–February).