Understanding Rahu / Ketu and their impacts on the life of an individual are one of the most difficult and challenging task for an astrologer especially in today’s context. To begin with, they are not even planets but just two imaginary astronomical points in the Zodiac. But in Vedic astrology they are treated as planets only. In fact the common reference in Vedic astrology is they are shadowy planets.
Rahu and Ketu are basically two mathematical points and are called the two lunar nodes and which are necessary to explain the astronomical phenomena of Lunar Eclipse and Solar eclipse. They are also known as Moon’s North node and Moon’s South node. The point where Moon crosses the ecliptic while traveling from south to north is known as Rahu, the North or the “ascending” node. The point where Moon causes the ecliptic while traveling from north to south is known as Ketu, the South or “descending” node.
The astronomical calculation necessary to compute the latitude of these two points are based on this concept of movement of Moon and is the cause of eclipses. The nodes are thus two points 180 degrees apart, which is why they are always located opposite to each other in an astrological chart or horoscope.
The ancient astrologers who were also professional astronomical observers felt enormous influences of the eclipse on the affairs of human beings on earth. They could not explain these cosmic influences based on the traditional 7 planets which they had identified in the cosmos with their naked eyes. They had realized that the relationship between the movements of earth, the moon and the Sun holds the key to the life on our planet. It will not be out of context to mention that it is not merely a statistical coincidence that Moon is just about the right size and right distance from the Earth to completely cover the Sun exactly during a total Solar eclipse.
Moon symbolizes the feminine or “Ying” principle and Sun symbolizes the masculine or Yang principle. The interplay between these two principles is creative forces behind all creation. The two lunar nodes are symbolic representations of this very imbalance between Yin and Yang principles of nature and represent dialectic of creation through the contradiction between Yin and Yang principles in nature.