Rahu Kaal

Rahu Kaal or the period of Rahu is a certain period of time every day that is considered inauspicious for any new venture according to Indian Vedic astrology.

In Hindu mythology, Rahu Kaala is one of the 8 segments of the day and considered inauspicious period in Indian astrology due to its associated with malefic, Rahu

In Hindu tradition, Rahu is a severed head of an asura, that swallows the sun causing eclipses. He is depicted in art as a serpent with no body riding a chariot drawn by eight black horses. Rahu is one of the navagrahas (nine planets) in Vedic astrology and is paired with Ketu. The time of day considered to be under the influence of Rahu is called Rahu kala and is considered inauspicious. In Vedic astronomy, Rahu is considered to be a rogue planet. The other name of Rahu is Bhayanka.

Astronomically, Rahu and Ketu denote the points of intersection of the paths of the Sun and the Moon as they move on the celestial sphere. Therefore, Rahu and Ketu are respectively called the north and the south lunar nodes. The fact that eclipses occur when the Sun and the Moon are at one of these points gives rise to the myth of the swallowing of the Sun and the Moon by the demon snake.

source: wikipedia