Editing Lunar node (section)

==Motion==
The [[line of nodes]], which is also the intersection between the two respective planes, rotates (precesses) with a period of 18.6 years or 19.35° per year. When viewed from the celestial north, the nodes move clockwise around Earth, I.e. with a [[retrograde motion]] (opposite to Earth's own spin and its revolution around the Sun).  So the time from one node crossing to the next (see [[eclipse season]]) is approximately a half-year minus half of 19.1 days -- or about 173 days.

Because the [[orbital plane]] of the Moon [[lunar precession|precesses]] in space, the lunar nodes [[nodal precession|also precess]] around the ecliptic, completing one revolution (called a ''draconic period'' or ''[[nodal period]]'') in {{convert|18.612958|year|day|abbr=off}}. (This is not the same as a [[saros (astronomy)|saros]] of 18.03 years) The same cycle measured against an inertial frame of reference, such as [[International Celestial Reference System]] (ICRS), a [[coordinate system]] relative to the [[fixed stars]], is 18.599525 years.