Ketu is considered as a neutral planet according to many scriptures of Vedic astrology; though some astrologers are of the opinion that it is a male/masculine planet. In practice, it tends to give results which may be more masculine than feminine, in most cases. It is considered as a fiery planet. Most Vedic astrologers associates it with Pitta (fire) element though some associate it with Vaata (air) element. In practice, it gives results corresponding to fire element in most cases. Ketu doesn’t have physical mass and it is a shadow planet. It is one of the most difficult planets among navagraha; when it comes to assessments, predictions and rectifications through remedies.
Looking at its characteristics/traits/significances; it represents disciples, orphans, mentally retarded people, physically handicapped people, dogs, goats, the occult, paranormal, spiritual growth, psychic perception, mysteries, corruptions, detachment, depression, fears, phobias, hallucinations, delays, losses, destruction, unfortunate events and diseases among other things.
Ketu rules Pitta (fire) element in body. Hence it may control the amount of energy or fire in body; though this job may primarily be done by Mars and Sun. Natives who have weak/afflicted Ketu in their horoscopes may suffer from health issues caused due to lack of fire element; as well as other issues. Poor digestion, laziness, lack of initiative, physical weakness, depression, restlessness, dental problems, ear problems; issues related to mental health; lack of spiritual growth and psychic perception are some of the problems that such natives may face.
On the other hand, if Ketu is strong in a horoscope, the native may witness good results related to digestion, initiative, aggression, physical energy, psychic perception, spiritual growth and many other things. In case Ketu is very strong; and Sun and/or Mars are also strong; the native may suffer because of too much fire element. Such native may face problems like too much aggression, overconfidence, impulsiveness, being violent, being argumentative, acidity, muscle cramps, high blood pressure, sleep disorders and ulcers among other things.
If Ketu is very strong as well as malefic; the native may suffer from fears, phobias, depression, split personality disorder, bipolar disorder, black magic, evil spirits, hallucinations and a number of other problems related to mental health and/or those related to the sphere of paranormal/occult. Ketu (when malefic and strong) may have the highest rate of getting people troubled through evil spirits, black magic, other worldly entities and a number of psychological disorders of various types; among navagraha (the nine planets).
Hence natives under its strong malefic influence may witness some of the most horrible, strangest and unbelievable types of problems happening to them. In many of these cases; such natives may actually go through such experiences but people around them may not believe them. Even when such malefic Ketu causes diseases or disorders; many of them may not even be diagnosed; let alone treating them. Such natives may suffer from various types of physical problems or disorders. However, their medical diagnosis as well as reports may show that everything is all right.
Hence the doctors may advise them that they may be suffering from some type of psychological disorder where they are assuming diseases and disorders within their bodies. In reality; these natives may actually be suffering from such diseases or disorders which may not be tested or diagnosed at those times. Likewise, one such native may actually have troublesome experiences with other worldly entities. However, no one may believe him and people may think he’s assuming such things.
Natives under strong influence of Ketu may practice as politicians, ministers, administrative officers, revenue officers, police officers, army officers, naval officers, air force officers, doctors, engineers, scientists, analysts, explorers, researchers, IT professionals, lawyers, physicians, surgeons, psychiatrists, therapists, consultants, advisors, astrologers, tantrics, psychics, healers, priests, religious heads, spiritual gurus, spiritual heads, preachers, teachers, chemists, pharmacists, investigators, detectives, spies, historians, archaeologists, geologists; professionals dealing in travel industry, airline industry, hotel industry, chemical industry, pharmaceutical industry; manufacturers of arms and defence equipment, hearing-aids, dog foods; and a number of other professionals.
Ketu may be strong or very strong in Aries, Leo, Scorpio, Sagittarius and Pisces; depending on its nakshatra and navamsha placements within these signs. It may perform well or very well in Cancer, Capricorn and Aquarius; depending on its nakshatra and navamsha placements within these signs. It may perform well or poorly in Gemini and Libra; depending on its nakshatra and navamsha placements within these signs. It may perform poorly or very poorly in Taurus and Virgo; depending on its nakshatra and navamsha placements within these signs.
Taking an example, Ketu may perform relatively well when placed in Pisces navamsha of Krittika nakshatra within the sign of Taurus. However, it may perform very poorly when placed in Taurus navamsha of Rohini or Virgo navamsha of Mrigashira nakshatra within the sign of Taurus. Taking another example, Ketu may be very strong when placed in Scorpio navamsha of Anuradha or Pisces navamsha of Jyeshtha nakshatra within the sign of Scorpio whereas it may be strong but not very strong when placed in Virgo navamsha of Anuradha nakshatra within the sign of Scorpio.
When malefic in horoscope, Ketu may form various type of defects. Among them; Kaal Sarp Yog, Guru Chandal Yoga, Grahan Yoga and Pitra Dosh are prominent ones.