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Celestial North (Article No: 111.  Published  08.11.07)

The stars seem fixed in relation to one another, yet they never stop moving. They orbit around our Galaxy, but because of Earth’s rotation the celestial vault changes in appearance from one hour to the next.

To find your bearings when looking for stars and other objects, one needs an infallible reference point. From Earth’s northern hemisphere, this point is where our north pole has its equivalent in the sky, a point that is visible every clear night, all year round, a point we call celestial north. Fortunately during our current time epoch, this invisible point lies very close (less than 1 degree) from a relatively bright star, called Polaris, excellently signposted in space by a group of stars we call the Plough. Two of these seven stars (part of the larger constellation of Ursa Major or the Great Bear) are known as the Pointers and direct us to Polaris, or the Pole Star. Like celestial north, neither Polaris nor the Plough set below the horizon as seen from our latitude, thus on a cloudless night one can find north with ease.

As the Plough is made up of bright stars, the shape is noticeable and very easy to find. Depending upon the time of day and season, the shape of the Plough can be found in various orientations, but its two pointers continue to point towards Polaris. Once you find the Plough, follow an imaginary line from the two pointer stars until you reach Polaris, the 1st bright and seemingly isolated star along that line. The travel distance is approximately 5 times the distance between the two Pointer stars. In mid November at 10pm try looking north and the image here will help you identify this. When celestial north is pinpointed, our Earth based cardinal points can be found easily. When facing Polaris, you are looking almost exactly due north. Turn your back on it and you view due south, while east and west can be deduced accordingly. Rise, transit and setting positions around your local horizon can now be identified. Clear skies!