Precession of the North Celestial Pole. Artwork of the constellations of the North Celestial Pole and the slow circular movement (red) of this Pole over a period of thousands of years. This movement is known as precession. Precession is the term for the way a rotating object (such as the Earth) wobbles in a precise and calculable manner. The current pole star is Polaris (centre right). Some 3000 years ago in around 2000 BC, the pole star was Draconis (lower centre). The time for one complete precession is shown as 23,667 years. The actual time is now thought to be closer to 25,700 years. The artworks of the constellations represent their mythical names. This artwork, which is based on the diagram in The Story of the Heavens (Robert Ball, 1886), was published in Pioneers of Science (Oliver Lodge, 1893).