Rahu is one of the Navagraha (nine planets) in Hindu
astrology. Rahu is a shadow planet and in astrology he is considered
inauspicious in Hinduism. He is the king of meteors and causes eclipses. The story of Rahu
begins with Mohini Avatar of Vishnu distributing the Amrit or Ambrosia that
came out after the churning of ocean or Samudra Manthan.
Rahu was the son of Viprachitti and Simhika. When Amrit
appeared at the end of the churning of the ocean, there was fight between Devas
and Asuras as to who will first consume it.
To solve the murky issue, Vishnu appeared as damsel Mohini and promised to
equally share the Amrit.
Amrit was first severed to Devas by Mohini. Rahu felt
something fishy about the whole episode. He disguised as a Deva and sat in
between Surya (sun god) and Chandra (moon god).
As soon as he had drunk Amrita, Surya and Chandra recognized
Rahu and alerted Mohini. The head of Rahu was cut off using the Sudarshana
Chakra.
As he had drunk amrit, he had become immortal. So his head
and body was placed separately in the sphere. Rahu has the head of a snake. In
some regions the head is that of a dragon.
Rahu periodically takes revenge by swallowing Surya and
Chandra causing eclipses.