Ketu

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.

Ketu's most direct address in devotional geography is a single small temple in the Kaveri delta of Tamil Nadu, at Keezhaperumpallam, one of nine shrines that together make up the Navagraha temple circuit built around Kumbakonam, each dedicated to one of the nine planetary powers of Hindu astrology. Unlike the anthropomorphic images of most Hindu deities, Ketu's consecrated image at the site follows an iconography distinct even from Rahu's: he is shown with a serpent's coiled tail in place of legs, a form that visually marks him as headless matter, body without governance, in contrast to Rahu's severed head shown alone or on a lion or serpent mount.

Pilgrims performing the Navagraha circuit, a practice believed to correct or balance the astrological influence of all nine planets in a single sequence of visits, generally treat the Ketu temple as addressing affliction connected with sudden loss, unexplained illness or obstacles attributed to a poorly placed node in a person's birth chart, with the rites performed there aimed at converting Ketu's disruptive potential into its other traditional aspect, detachment and release. The temple's specific dedication to a graha with no physical body in the sky, worshipped nonetheless in stone and ritual at a fixed geographic address, illustrates how thoroughly Hindu astrology's abstract astronomical points were given a concrete devotional home.