Orbital node

Node is called the intersection of the path of an astronomical object with a reference plane ( usually the ecliptic plane in the solar system ).

The point at which the train pierces the reference plane from south to north is called the ascending node. The point at which the train pierces the reference plane from north to south is called descending node. North denotes the northern direction of the Earth's axis. If the reference plane in no relation to the ecliptic, a correspondingly different definition for ascent and descent is chosen.

The straight line joining two nodes is the line of nodes.

The location of the ascending node with respect to the vernal equinox, the argument of the node ( node length, here in the graph with ☊ called ), and location of the ellipse vertex to node line, the argument of periapsis ( ω ), are two path elements (the six to fully are description of an ideal Kepler's planetary orbit necessary).

The period between two passages of a celestial body by the same node is the Drakonitische period.

If the node with a conjunction together, which leads to coverage, ie a transit or an occultation:

• If the new moon near a lunar node, it comes to solar eclipse, the full moon is near a node, the lunar eclipse.
• Are Mercury and Venus during inferior conjunction near their railway junction, there is a Mercury or a transit of Venus.
• For the Earth, the ecliptic itself forms the orbital plane, and it can not define a node. In - heliocentric time ago we saw the equinoxes as the "knot of the (apparent) sun's path " indicates the reference plane this was the celestial equator.