The Severed Tail: The Descending Node as a Shadow-Planet

Ketu is the tail to Rahu's head, the lower half of the demon Svarbhanu, who was beheaded by Vishnu for stealing a sip of the gods' nectar, and who survives as two of the nine grahas (planetary powers). Astronomically, Ketu is not a body at all but the descending lunar node, one of the two points where the paths of the sun and moon cross and at which eclipses become possible; he marks a place on the ecliptic rather than occupying a planet.

The tradition reads the pair as complementary lacks: where Rahu is an appetite that can never be satisfied because it has no stomach, Ketu is a body that cannot act because it has lost its head. Jyotisha accordingly associates Ketu with loss, detachment, sudden cutting-off, and with comets and meteors, but also, in a very different reading, with spiritual liberation (moksha), the renunciation that follows when worldly attachment is severed. He is the most inauspicious of the grahas to some schools and the most inwardly liberating to others, and the tradition does not reconcile the two readings.