Castor the Star

Castor and it's twin star Pollux are in the Gemini constellation and are easily found as there are two ways of locating them using other well known constellations.

Firstly using Orion imagine a line from Rigel through Betelgeuse which will lead you to Castor, the bright star just below and to the left is it's twin star Pollux.

Secondly using the Big Dipper (also commonly known as the plough), imagine a line from Megrez through Merak which will lead you to Pollux, Castor is the next brightest star just above and to the right.


As an aside the big dipper can also be used to find Polaris by imagining a line from Merak through Dubhe and then extending it for five times the distance between the two Pointers. Polaris is a very important star in the night sky as being nearly in a direct line with the axis of the Earth's rotation above the North Pole it stands almost motionless in the night sky. All the stars of the Northern sky appear to rotate around it making it an excellent fixed point for celestial navigation and astrometry.

Gemini and Orion can be seen in the northern hemisphere in the Winter and Spring months, the big and little dipper can be seen all year round.

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