The astronomical north is the direction pointing towards the Earth's North Celestial Pole. This pole is defined as the point on the celestial sphere that is directly above the Earth's geographical North Pole.

The exact location of the astronomical north pole varies slightly over time due to the precession of the Earth's axis. This precession is caused by the gravitational forces exerted by the Sun and Moon on the Earth's equatorial bulge. The precession period is about 25,800 years.

The astronomical north pole is important in astronomy and navigation. It is used to define the celestial coordinate system, which is the system of coordinates used to specify the positions of objects in the sky. It is also used to define the direction of true north, which is the direction that points towards the astronomical north pole.