orbital node

The type and length of an eclipse depend upon the Moon's location relative to its orbital nodes.

(It will exhibit 180 rotational symmetry about the orbital nodes.)

An orbital node is one of the two points where an orbit crosses a plane of reference to which it is inclined.

The nodal period of a satellite is the time between successive passages of a satellite through successive orbital nodes.

This torque does not reduce the inclination; rather, it causes a torque-induced gyroscopic precession, which causes the orbital nodes to drift with time.

The largest component of Earth's nutation has a period of 18.6 years, the same as that of the precession of the Moon's orbital nodes.

The lunar nodes are the orbital nodes of the Moon, that is, the points where the orbit of the Moon crosses the ecliptic.

An eclipse of the Sun on Pluto can occur only when one of the satellites' orbital nodes, the points where their orbits cross the dwarf planet's ecliptic, is lined up with the apparent position of the Sun as seen from Pluto.

This maneuver requires a change in the orbital velocity vector (delta v) at the orbital nodes (i.e. the point where the initial and desired orbits intersect, the line of orbital nodes is defined by the intersection of the two orbital planes).