Earth and the Moon

Mapping the Night Sky

What is the North Star?

The North Star is any star near the spot in the sky called the north celestial pole, the place that Earth’s rotational axis is pointing toward. Right now, and for the past several centuries, a Cepheid variable star called Polaris has been very close to the pole, and thus has served as a good north star. Earth’s rotational axis changes its pointing location across the sky over the millennia, however. Thousands of years ago, while ancient Egyptian culture thrived, the North Star was a dimmer star called Thuban. Between then and now, there have been stretches of many centuries when there was no useful North Star at all.


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