Rahu is the personification of an astronomical point, the moon’s north node. He is known as the deity who causes eclipses.    The north and south nodes are the two points where the orbits of the moon and the sun (ecliptic) intersect.  Eclipses occur when the new or full moon is near one of the lunar nodes.   

Rahu is a wrathful deity (krodhadevata), engulfed in flames, black in color.  A raven sits on the top of his nine heads, which represent the nine planetary forces in Vedic astrology (navagrahas), of which Rahu is one. He is half man and half serpent, and is shown in the ocean causing the chaos and destruction for which he is noted.  His body is covered with eyes which symbolize his ability to see into every corner of the universe.  

In his right hand Rahu holds a chakra weapon, with which he attacks the sun or moon, thus causing them to disappear during an eclipse.  In his left hand he holds a vajra noose, made from a rope whose ends are capped with hook and vajra.  Both hands have index and pinky fingers raised in the karana mudra used to expel demons, remove negative energy and ward off evil indicating his ability to bind and destroy all harmful spirits or demonic enemies of the teachings. This image is based on a Qing dynasty painting.