Like Rahu, Ketu is also an imaginary planet or a node that is positioned diametrically opposite Rahu. The North node is called Rahu while the South node is known as Ketu. It is believed to represent the tail of demon.
The South node or Ketu is regarded as a point where the native’s bad Karma from his past life is concentrated and the place where a person reaps the results of his selfish and egoist deeds committed in the past. The other side of Ketu represents the tendency of a human being to incline towards Moksha or liberation and also mastery of secret and mysterious mystic knowledge.
Rahu and Ketu are well known for conferring on the native sudden and unexpected results. Astrologically when Ketu, Sun and the Moon lie in the same zodiacal longitude a lunar eclipse takes place. Rahu is especially inimical towards the Sun and Ketu towards the Moon.
The professions ruled by Ketu are those of magicians, medical practitioners, astrologers and doctors. Both Rahu and Ketu, the mystical imaginary nodes, are representative of the mysterious forces in the cosmos and display karmic and spiritual influences in the birth chart or horoscope.
Like Rahu, Ketu also does not rule any particular zodiac sign since it has no physical appearance. However it is considered to be exalted in the sign of Sagittarius. Some astrology scholars are of the view point that Ketu is exalted in Scorpio. Likewise it is considered to be in a debilitated position in Gemini or Taurus. Ketu is also considered very influential and strong in the Jupiter sign.
The planet Ketu is especially known for paranormal activities and spirituality. The native influenced by this planet is usually gifted with spiritual achievements. The other interests of the native also display an inclination towards religious and secret awareness including supernatural powers and ghost related subjects. Such individuals have also been known to have great healing power and the ability to heal through their spiritual and tantric power.
The time period allotted to Ketu’s transit or mahadasha is seven years and the representative gemstone is the Cat`s eye (Lahsunia).
Ketu, if placed favorably and in a strong position in a horoscope bestows on the native a lot of luxury, wisdom and intuition. If it is unfavourable it can cause unnecessary depression, poor concentration, boundless worries, anxiety and ghost related problems.