Celestial pole

Because of a phenomenon known as the precession of the equinoxes, the poles trace out circles on the celestial sphere, with a period of about 25,700 years.

To take into account such movement, celestial pole definitions come with an epoch to specify the date of the rotation axis; J2000.0 is the current standard.

It will remain a good approximation for about 1,000 years, by which time the pole will have moved closer to Alrai (Gamma Cephei).

In about 5,500 years, the pole will have moved near the position of the star Alderamin (Alpha Cephei), and in 12,000 years, Vega (Alpha Lyrae) will become the "North Star", though it will be about six degrees from the true north celestial pole.

To find the correct side, imagine that Archernar and Canopus are both points on the circumference of a circle.

If Canopus has not yet risen, the second-magnitude Alpha Pavonis can also be used to form the triangle with Achernar and the pole.

In this case, go anticlockwise from Achernar instead of clockwise, form the triangle with Canopus, and the third point, the pole, will reveal itself.

These are marked in astronomy books as the Large and Small Magellanic Clouds (the LMC and the SMC).

A line from Sirius, the brightest star in the sky, through Canopus, the second-brightest, continued for the same distance lands within a couple of degrees of the pole.

The north and south celestial poles and their relation to axis of rotation , plane of orbit and axial tilt .
Diagram of the path of the celestial north pole around the ecliptic north pole . The beginning of the four " astrological ages " of the historical period are marked with their zodiac symbols : the Age of Taurus from the Chalcolithic to the Early Bronze Age , the Age of Aries from the Middle Bronze Age to Classical Antiquity , the Age of Pisces from Late Antiquity to the present, and the Age of Aquarius beginning in the mid-3rd millennium.
Over the course of an evening in the Northern Hemisphere , circumpolar stars appear to circle around the north celestial pole. Polaris (within 1° of the pole) is the nearly stationary bright star just to the right of center in this star trail photo.
A series of shots show the rotation of Earth's axis relative to the south celestial pole. The Magellanic Clouds and the Southern Cross are clearly visible. Near the end of the video, the Moon rises and illuminates the scene.
The south celestial pole over the Very Large Telescope [ 3 ]
Locating the south celestial pole