Planetocentric coordinates are coordinates used to locate a point on the surface of a planet or satellite during dynamic or astrometric studies. The planetocentric longitude of a point on the surface is the dihedral angle between the meridian of the point and a conventional origin meridian. It is counted from the origin meridian from 0° to 360° in the direction of rotation of the body. The planetocentric latitude of a point on the surface is the angle made by the vector joining the centre of the body at this point and the equatorial plane of the body. It is counted from the equator of the body from 0° to +90° towards the north pole and from 0° to -90° towards the south pole.