An orbital node is one of the two points where an inclined orbit crosses a plane of reference (e.g. the equator for geocentric orbits, the ecliptic for heliocentric orbits). Nodes do not exist for orbits with inclination equal to zero (equatorial orbits or ecliptic orbits). Two bodies with a slight difference in mass orbiting around a common barycenter. ... In celestial mechanics, the plane of reference is the plane from which orbital elements are defined. ... The equator is an imaginary circle drawn around a planet (or other astronomical object) at a distance halfway between the poles. ... Geocentric orbit refers to any object revolving around Earth, such as the Moon or artificial satellites. ... The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ... A heliocentric orbit is an orbit around the sun. ... Inclination in general is the angle between a reference plane and another plane or axis of direction. ... Equatorial orbit is an orbit with inclination to the plane of reference (i. ... Eclipitic orbit is an orbit with inclination to the plane of reference (i. ...

The ascending (or north) node is where the object moves north from the southern hemisphere to the northern, the descending (or south) node is where the object moves back south. The line of nodes is the intersection of the object's orbital plane with the plane of reference, and runs between the ascending and descending nodes. Compass rose with north highlighted and at top North is one of the four cardinal directions, specifically the direction that, in Western culture, is treated as the primary direction: north is used (explicitly or implicitly) to define all other directions; the (visual) top edges of maps usually correspond to the... Southern Hemisphere The Southern Hemisphere is the half of a planets surface (or celestial sphere) that is south of the equator (the word hemisphere literally means half ball). On Earth it contains five continents (Antarctica, Australia, most of South America, parts of Africa, and Asia) as well as four... A compass rose with South highlighted South is most commonly a noun, adjective, or adverb indicating direction or geography. ...

“north” is designated by the Axis of the Earth, both referring to equator or ecliptic. Reference to other planes will need an adequate definition.

The symbol of the ascending node is ☊, descending node is ☋. These are also known as the "Dragon's Head" and the "Dragon's Tail" respectively.

The lunar nodes are subject to lunar precession, which is the gradual shift westward because of the gravitational pull of the Sun upon the Moon. (See also: eclipse) The lunar nodes are the orbital nodes of the Moon, that is, the points where the orbit of the Moon crosses the ecliptic (which is the apparent path of the Sun across the heavens against the background stars). ... The moons elliptical orbit precesses about once in just under 9 years. ... In physics, gravitation or gravity is the tendency of objects with mass to accelerate toward each other. ... The Sun is the star at the center of Earths solar system. ... Bulk composition of the moons mantle and crust estimated, weight percent Oxygen 42. ... The French 1999 eclipse An eclipse (Greek verb: ekleipô, to vanish) is an astronomical event that occurs when one celestial object moves into the shadow of another. ...

Fig. 1: The line of nodes is the green line in this diagram.

Orbital parametres, illustrated. ... Orbital parametres, illustrated. ...

See also

• Lunar node – the orbital nodes of the Moon.