Precession of the equinoxes

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The precession of the equinoxes describes an astronomical phenomenon whereby the earth appears to wobble on its axis relative to the stars. This wobble is very slow.[1] The result of this is that the position of stars and constellations overhead at any particular time gradually changes over the years. For example, the constellation that rises above the horizon at the spring equinox gradually cycles through the signs of the zodiac backwards. The star around which all the other stars seem to revolve (to an observer on Earth) also changes over time, meaning that Polaris, or the present North Star, has not always been the star closest to north, and will be replaced by other stars in the future. The Earth's axis pointed to the star Thuban in the year 3000 B.C.[2]

List of selected North Stars[3]

Approximate year Common name Astronomical name
3000 BC Thuban Alpha Draconis
1000 BC Kochab Beta Ursa Minoris
2000 AD Polaris Alpha Ursa Minoris

List of selected South Stars

Approximate year Common name Astronomical name
4000 BC Achernar Alpha Eridani
2000 AD n/a Sigma Octans