Eclipses occur only near the lunar nodes: Solar eclipses occur when the passage of the Moon through a node coincides with the new moon; lunar eclipses occur when it coincides with the full moon. The Moon's distance to the nodes will be less than about 1.5°.
The lunar nodes precess rather quickly around the ecliptic, completing a revolution (called a draconitic or nodical period, the period of nutation) in 6793.5 days or 18.5996 years (note that this is not the saros eclipse cycle).
Since the ascending node is the point of intersection between the ecliptic and the plane of the lunar orbit where the Moon is ascending from the South to the North, it is sometimes called the North node. In ancient European texts, it is referred to as the dragon's head (Caput Draconis, or Anabibazon). The symbol of the ascending node is , the astronomical and astrological symbol for the Dragon's head. Similarly the descending node is the point where the Moon is descending from North to South, and is sometimes referred to as South node. It is also known as the dragon's tail (Cauda Draconis, or Catabibazon), and its symbol is the inversion of that of the ascending node: . Note that the so-called North node may in fact lie South of the South node in the course of the nodal cycle.
Their significance can vary widely between approaches. In general, the north node is viewed a point of opportunity for growth and development and self help, while the south node is thought to represent karmic repression or tendencies that restrict growth. The north node carries the positive and beneficial tone of Jupiter, while the south node expresses the restrictions and obstacles of Saturn. Another view is that the north node represents positive objectives and the south node denotes the easy way out with little opportunity for growth. The two nodes together are most commonly referred to simply as the nodal axis, the lunar nodes, or the moon's nodes.
In Vedic astrology, Rahu (north node) is considered to be similar to Saturn, and Ketu similar to Mars. Rahu signified materialism and desires, whereas Ketu signifies obstacles in the material realm but spiritual tendencies.