As per Hindu astrology, Rahu and Ketu have an orbital cycle of 18 years and are always 180 degrees from each other orbitally (as well as in the birth charts). Astronomically, Rahu and Ketu denote the points of intersection of the paths of the Sun and the Moon as they move on the Celestial Sphere. Therefore, Rahu and Ketu are respectively called the North and the South Lunar Nodes. That eclipses occur when the Sun and the Moon are at one of these points gives rise to the understanding of swallowing of the Sun and the Moon by the snake. Rahu is responsible for causing the Eclipse of the Sun.
Both Rahu and Ketu are the shadow planets in the Horoscope. Like other Planets, Rahu and Ketu do not have their separate identity. However, it is believed that Rahu and Ketu have malefic effects on the natives if they aren't correctly placed in the Horoscope. As they change their position in the Horoscope, they can have a negative or positive effect on the person. Rahu and Ketu are important if they are conjoined with any Planet. If they are conjoined, they provide results of the Planet which aspects them. Today, 90% of us are afraid of Rahu Ketu. We have a physical resemblance to all the Planets and Nakshatras in Vedic Astrology and their presence is not only physical but obvious too.
The Planet Rahu is one of the nine major Celestial bodies (navagraha) in Hindu texts. Unlike most of the others, Rahu is a shadow entity and the one that causes eclipses and is the king of meteors. This Rahu represents the ascension of the Moon in its precessional orbit around the Earth. Rahu is North Node of the Moon. Rahu has no physical shape. It is an imaginary Planet but considering the importance of Rahu in Astrology, it has been allocated the status of the Planet by Rishis in our ancient India. Rahu is usually paired with Ketu which is also considered to be a shadow Planet. The time of day considered to be under the influence of Rahu is called Rahu Kalam and is considered inauspicious.
Rahu is a planet full of tamasik infatuation in human life. A person affected by Rahu or Rahu mahadasha will be more in to materialistic pleasure and wordly desires. Basically, you have no spirituality but you completely surrender to material life only. Fame, greed, obsession, manipulation, disease, inertia, foreign language, harsh speech, eating of non-veg, speaking lies, theft, problems related to abdomen, politics, planning and plotting, cheating, mystery, illusion, crime, etc are the topics related to Rahu.
Ketu is generally referred to as a "shadow" Planet. It is believed to have a tremendous impact on human lives and also the whole creation. In some special circumstances it helps someone achieve the zenith of fame. Ketu is often depicted with a gem or star on his head signifying a mystery light. Ketu is South Node of the Moon. Ketu doesn’t own any house or rashi in horoscope unlike Rahu. All the Houses and Rashis are only ruled by the seven Planets. However, few astrologers believe that Nodes also own the Houses and Signs. Well, Ketu doesn’t own any Sign unlike Rahu, hence it represents Lord of Sign only. Ketu rules over Ashwini, Magha and Moola Nakshatras. However, some believe that Ketu gets exalted in Scorpio or Sagittarius and gets debilitated in Taurus or Gemini. If Ketu occupy the beneficial houses in the horoscope, then it will give the good results and vice versa. Ketu is maternal grandfather, birth in low caste, evil thoughts and actions, marrying other caste, dissatisfaction, lack of courage and concentration, pain, gastric troubles, but gives spirituality as well.
