Ketu is what remains of the body of Rahu.

Ketu is a headless half-planet, shadowy as Rahu and malefic, though not as malefic as Rahu. It is therefore considered a moksha-karak (cause of liberation from the cycle of birth and death). It bestows spiritual tendencies, ascetism and nonattachment to worldly desires and ambitions.

Ketu is also a half-planet that bestows wisdom, powers of discrimination, and gyana - spiritual knowledge, the knowledge of the self. It gives psychic abilities to its natives and makes them masters of the healing arts, natural healing, healing herbs, spices, foods, tantric healing, healing of persons possessed by evil spirits, ghosts and astral forces. Ketu natives also have the ability to go unnoticed or merge into the crowd of common folk.

Ketu's effects are similar to those of Mars, but this is only one way of describing the malefic effect and power of Ketu.

Ketu can be more destructive if it is inauspiciously positioned in the horoscopes. Ketu destroys the potency of the planet with which it is conjunct making the planet behave in an uncontrollable manner. It is tamasik, of hybrid generation, malefic, awful, and devious in nature.

Ketu is neither feminine nor masculine, wind-dominated, aged, powerful at night, animalistic, obsessive, compulsive and unconscious in behavior. It is associated with a smoky-grey colour and Ketu's gemstone is cat's-eye. Ketu rules number 7 in indian numerology.