The lunar nodes are the points where the moon's path in the sky crosses the ecliptic, the sun's path in the sky

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 ascending node is where the moon crosses to the north of the ecliptic. The descending node is where it crosses to the south.

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 passage coincides with the full moon. For an eclipse to occur, the Moon's distance to the nodes must be less than about 1.5°.^[1]

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).

[edit] Names and symbols

The nodes are called by different names in different areas of the world.

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.

In Hindu astronomy, the ascending node is called Rahu and the descending node is called Ketu.

[edit] Extreme declinations

The lunar orbit is inclined by about 5 degrees on the ecliptic: hence the Moon can be up to about 5 degrees North of the ecliptic, and as much South of the ecliptic. The ecliptic is inclined by about 23.4° on the celestial equator, the plane that is perpendicular to the rotation axis of the Earth. As a consequence, once during the 18.6-year nodal period, when the ascending node of the Moon's orbit coincides with the vernal equinox, then the Moon reaches extreme northern and southern declinations. Then it also has its extreme northern and southern azimuth points of rising and setting on the horizon; its extreme lowest and highest altitude when crossing the meridian; and potentially extreme late first sightings of the new moon. Furthermore, occultations by the Moon of the bright star group the Pleiades, which are over 4° North of the ecliptic, occur during a comparatively brief period once every nodal period.

[edit] Astrological significance

The lunar nodes are of major astrological significance in Vedic astrology, and generate growing intrest in Western astrology. Usually only the north node is marked in horoscopes, as the south node is by definition always located at the opposite point in the astrological chart. In Vedic Astrology, the north node is called Rahu and the south node Ketu, and both are marked in the chart.

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. New perspectives attribute equal weight to the North and South Nodes, seeing them as points of balance rather than positive or negative associations.

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.

However when in conjunction with other planets both Rahu and Ketu are known to give malefic results in material life e.g. Conjunction of Rahu or Ketu with Venus is bad for marital life, conjunction with moon is harmful for health of a native or his/her mother and /or mental wellbeing of either of them.

To reiterate: In Vedic (Indian, Hindu) astrology (formally called "jyotish," the "science of light"), the nodes are both malefic, in somewhat varying degrees. In the West, however, the North Node is considered to be benefic, while the South Node, not so much. In addition, some jyotishis (practitioners of Vedic astrology) hold that the discoveries of the three outer planets (at this point, Uranus, Neptune, and Pluto--Eris and others are not firmly established as yet, at least as to meaning) are considered unnecessary. Even Western jyotishis will say that Ketu has some of the qualities of Uranus, for example. Other Western jyotishis and a few in India do use the outer planets, and hold that the Nodes are their own thing, not being planets being just one part of this, albeit the most important part.

The Nodes are, as nothing else is, an interrelationship among Sun, Moon, and Earth. As such, in some ways they hold less significance against the backdrop of the stars, which is of much greater importance in sidereal (e.g., Vedic) astrology than it is in tropical(Western) astrology.

[edit] See also

• Astrology
  • Astrological aspects
• Eclipse
• Horoscope
• Lunar standstill
• Orbit of the Moon
• Natal chart

[edit] References

1. ^ André Danjon. Astronomie Générale. 2nd Edition, Paris, 1980.

[edit] External links

• Sun and Moon Polar Applet, showing moonrise/moonset azimuths
• Astronomy Answers: What are the standstills of the Moon?
• Eclipses, Cosmic Clockwork of the Ancients