Keywords |
  • Universe


Precession is a modification in the direction of the axis of rotation of a body.
Because of the gravitational attraction of the Moon, the Sun and the planets on the Earth, its axis of rotation forms a cone in space, taking 25,800 years to do so. Currently, the Earth's axis of rotation points more or less to the Pole Star, which therefore indicates the north, but because of precession this has not always been the case: in Homer's time, Kochab in the Ursa Minor constellation was the closest to the celestial north pole; when the pyramids were being built, it was Thuban (Alpha Draconis) that was the closest to the pole in 2700 BC; in about 10,000 years, it will be Vega that will indicate the north.



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