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Gemini - the Twins


Mythology - Gemini has long been associated with the advent of fair sailing weather and the twins are often depicted at the entrance to harbours. Zeus, disguised as a swan, seduced Leda who laid an egg from which Helen and Pollux were born. At the same time she also gave birth to Castor and Klytemnestra, children of her husband Tyndareus. Since Pollux was the child of a god, he was immortal whereas Castor was mortal. The boys grew close as brothers and became famous for their athletic abilities, notably horsemanship and boxing. The Olympic games came about as a result of their prowess. They took part in Jason's search for the golden fleece as argonauts. A rivalry between the brothers and their twin cousins caused the death of the mortal Castor. In his grief, Pollux asked Zeus to permit him to die so he could remain with his brother. Zeus placed the boys in the sky as a symbol of brotherly love and devotion.
Stars - Castor (alpha geminorum) is a system of six stars in reality. Through a telescope the star resolves into two bright points, each of which is a binary pair (not observable). A faint pair of red dwarfs orbits these four stars. Mebsuta (epsilon geminorum) is a wide double visible in binoculars. Wasat (delta geminorum) is a close 3rd and 8th magnitude pair, the primary being a red giant variable.
Deepsky - M35 is a superb open cluster in Gemini, easily visible in binoculars as at triangular blob. A small telescope resolves this into hundreds of stars. Very nearby is the fainter NGC 2129. The Eskimo Nebula (NGC 2392) is a fascinating telescopic object but is too faint to see in binoculars. A telescope of 6” and greater will show a fur “hood” round a round face.
Visibility - The best time to see Gemini is from February through to April