Rahu Ji

Rahu is one of the Navagraha, personifying the ascending lunar node, astronomically the point where the Moon's orbit crosses the ecliptic moving northward, and is held responsible in myth for solar eclipses.

He is called the "king of meteors," and, together with Ketu, is understood as one of the two halves of the demon Svarbhanu, "he who darkens the luminaries," whose severed head Rahu is said to be.

He is typically shown as a fearsome, dragon- or serpent-headed figure with no body below the neck, sometimes riding a chariot pulled by eight black horses, an image that directly recalls his mythological origin as a decapitated head.

During the Samudra Manthana, the churning of the cosmic ocean of milk for the elixir of immortality, the asura Svarbhanu disguised himself as a deva to receive a share of the amrita. Surya and Chandra alerted Vishnu, who beheaded him before the elixir could pass his throat; the head, already immortal from the drops it had swallowed, became Rahu, while the headless body became Ketu. Because he is only a head, Rahu is said to swallow the Sun or Moon during an eclipse only for them to pass straight through his severed throat, the cycle repeating with each recurrence.

Rahu and Ketu are the two halves of the single asura Svarbhanu, making them a permanently linked pair, always positioned opposite one another, 180 degrees apart, in both the sky and in astrological charts.

As a "shadow planet" rather than a physical body, Rahu occupies a special place among the Navagraha, associated in Vedic astrology with obsession, illusion, ambition and sudden, disruptive change, and is propitiated to temper these effects.

He is worshipped almost exclusively as part of the Navagraha set rather than through independent temples, though a small number of dedicated Rahu shrines exist in Tamil Nadu as part of regional Navagraha pilgrimage circuits.