Cardinal Points

6.13 - Understand, in relation to astronomical observations, the terms:
a) cardinal points

A cardinal point is the same as compass points. We refer to north as celestial north, south as celestial south etc.

It is quite an easy system except when it comes to the Moon and other bodies. This is quite helpful to know even if it is not in the specification.

The IAU, International Astronomy Union, decided the Moon's reference points would be the same as if looking at Earth from the Northern Hemisphere. They say the north pole is the axis of rotation. So west on the Moon is east in the sky and east on the moon is west in the sky.

This is a contentious issue among astronomers as this does not automatically apply to the Sun for historical reasons. Venus and Uranus are also contentious because of their axis and rotation. Don't worry about it.

 

Links