# Orbital node

Nodeascending nodenodesdescending nodeline of nodesnodal lineorbital nodesascendingascending and descending nodesascending lunar node
An orbital node is either of the two points where an orbit intersects a plane of reference to which it is inclined.wikipedia
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### Non-inclined orbit

equatorial orbitequatorialEcliptic orbit
A non-inclined orbit, which is contained in the reference plane, has no nodes.
As these orbits lack nodes, the ascending node is usually taken to lie in the reference direction (usually the vernal equinox), and thus the longitude of the ascending node is taken to be zero.

### Ecliptic

ecliptical orbitsecliptic planeplane of the ecliptic
For the orbit of the Moon around Earth, the plane is taken to be the ecliptic, not the equatorial plane.
The crossing from south to north is known as the vernal equinox, also known as the first point of Aries and the ascending node of the ecliptic on the celestial equator.

### Longitude of the ascending node

right ascension of the ascending nodelongitude of ascending nodenode
This is done by specifying the longitude of the ascending node (or, sometimes, the longitude of the node.)
Here, n= is a vector pointing towards the ascending node.

### Orbital elements

orbital parametersorbital elementKeplerian elements
The position of the node may be used as one of a set of parameters, called orbital elements, which describe the orbit.

### Lunar node

nodeNorth Nodelunar nodes
The gravitational pull of the Sun upon the Moon causes its nodes to gradually precess westward, completing a cycle in approximately 18.6 years.
A lunar node is either of the two orbital nodes of the Moon, that is, the two points at which the orbit of the Moon intersects the ecliptic.

### Euler angles

yawEuler angleTait–Bryan angles
The geometrical definition (sometimes referred to as static) begins by defining the line of nodes as the intersection of the planes xy and XY (it can also be defined as the common perpendicular to the axes z and Z and then written as the vector product N = z \times Z).

### Lunar precession

precess18.6 and 8.85 yearslunar apsidal precession
The gravitational pull of the Sun upon the Moon causes its nodes to gradually precess westward, completing a cycle in approximately 18.6 years.
The period of the lunar nodal precession is defined as the time it takes the ascending node to move through 360° relative to the vernal equinox (autumnal equinox in Southern Hemisphere).

### Eclipse

eclipsestotal eclipseeclipsing
Because the orbital plane of the Moon is tilted with respect to the orbital plane of the Earth (the ecliptic), eclipses can occur only when the Moon is close to the intersection of these two planes (the nodes).

### Orbit of the Moon

Moon's orbitits orbitorbit
For the orbit of the Moon around Earth, the plane is taken to be the ecliptic, not the equatorial plane.
The draconic month is the time from ascending node to ascending node.

### Orbit

orbitsorbital motionplanetary motion
An orbital node is either of the two points where an orbit intersects a plane of reference to which it is inclined.

### Intersection (Euclidean geometry)

intersectsintersectintersecting
An orbital node is either of the two points where an orbit intersects a plane of reference to which it is inclined.

### Plane of reference

reference planeplaneplanes
For the orbit of the Moon around Earth, the plane is taken to be the ecliptic, not the equatorial plane. An orbital node is either of the two points where an orbit intersects a plane of reference to which it is inclined.

### Coplanarity

coplanarnon-coplanarcontained
A non-inclined orbit, which is contained in the reference plane, has no nodes.

### Geocentric orbit

GeocentricEarth orbitEarth-orbit

### Earth

Earth's surfaceterrestrialworld
For the orbit of the Moon around Earth, the plane is taken to be the ecliptic, not the equatorial plane.

### Heliocentric orbit

Heliocentrictrans-Mars injectionsolar orbit

### Invariable plane

common orbital alignmentinvariable plane of the Solar System“invariable” axis

### Solar System

outer Solar Systeminner Solar Systemouter planets

### Primary (astronomy)

central bodyprimaryprimary body

### Unicode

Unicode StandardUnicode Transformation FormatThe Unicode Standard
The symbol of the ascending node is (Unicode: U+260A, ☊), and the symbol of the descending node is (Unicode: U+260B, ☋).

### Latin

Latin languageLat.la
In medieval and early modern times the ascending and descending nodes were called the dragon's head (Latin: caput draconis, Arabic: ra's al-jauzahar) and dragon's tail (cauda draconis), respectively.

### Arabic

Arabic languageArabic-languageArab
In medieval and early modern times the ascending and descending nodes were called the dragon's head (Latin: caput draconis, Arabic: ra's al-jauzahar) and dragon's tail (cauda draconis), respectively.

### Moon

lunarthe MoonLuna
, p. 141;, p. 245. These terms originally referred to the times when the Moon crossed the apparent path of the sun in the sky.

### Greek language

GreekAncient GreekModern Greek
The Greek terms αναβιβάζων and καταβιβάζων were also used for the ascending and descending nodes, giving rise to the English words anabibazon and catabibazon.

### English language

EnglishEnglish-languageen
The Greek terms αναβιβάζων and καταβιβάζων were also used for the ascending and descending nodes, giving rise to the English words anabibazon and catabibazon.