Definition

A point that is the start or end point of a line segment. In ASTRONOMY, one of the two points of intersection of the ORBIT of a PLANET, PLANETOID, or COMET with the ECLIPTIC, or of the ORBIT of a SATELLITE with the plane of the orbit of its primary. That point at which the body crosses to the north side of the reference plane is called the ascending node; the other, the descending node. The line connecting the nodes is called LINE OF NODES. Also called NODAL POINT. See REGRESSION OF THE NODES. In OCEANOGRAPHY, that part of a STANDING WAVE where the vertical motion is least and the horizontal VELOCITIES are greatest. See PARTIAL NODE. In optics, a NODAL POINT.