The constellation of Gemini, the twins, is well placed at this time of year from the northern hemisphere. It sits to the south-west of Orion, the hunter, in-between Cancer, the crab, and Auriga, the charioteer. The chart shows the view looking south from London at 2100 GMT on Monday night. Gemini is named after the twins Castor and Pollux. In Greek mythology, they were born as twins even though both had a different father. Castor was the mortal son of the king of Sparta, while Pollux was the divine offspring of Zeus. The two brightest stars in the constellation are named after them. Castor is a blue-white star, 53 light years from Earth. Although it appears singular to the naked eye, telescopes have revealed that it is a collection of six stars in orbit around each other. Pollux is an individual star that shines with a faintly orange hue. It is 34 light years from Earth. Together they mark out the heads of the twins. The constellation itself is one of the 48 star patterns noted by Ptolemy in the second century AD, and is also visible from the southern hemisphere. From Sydney, look to the north; Gemini will be diving head first across the meridian.