Navagraha are nine heavenly bodies and deities that influence human life on Earth according to Hinduism and Hindu astrology. Rahu and Ketu unlike other Navagraha members do not rule upon a physical planet. They are chhaya graha, which means shadow planets, and hence are responsible for eclipses of the sun and moon. The two shadow planets were once a single entity. Svarbhanu, an asura, who aspired to become invincible, disguised himself as a deva to consume the nectar of immortality. Surya and Chandra due to their celestial light were able to identify the imposter among them and informed Mohini, the female form of Lord Vishnu.
By the time Mohini used her Sudarshan Chakra to behead the asura, Svarbhanu had already consumed the nectar, thus making him immortal. Due to this the decapitated head and the body came to be known as two different entities called Rahu and Ketu, respectively.
Rahu is the decapitated head of the asura, Svarbhanu, and it represents the northern lunar node. Rahu is responsible for the eclipse of the sun, which was once interrupted by a young Hanuman, who wanted to consume the sun, thinking the bright flaming ball was a giant fruit. The Navagraha is depicted without a body, mounted on his vahana, a black lion.
Ketu is the headless body of the asura, Svarbhanu, and it represents the southern lunar node.
Ketu is responsible for the eclipse of the moon, where the deity is said to completely swallow the lunar celestial body. The Navagraha is depicted without a head, with fours arms and a serpent’s tail instead of legs, mounted on his vahana, a vulture.
