Ketu or Dragon's Tail or South Node represents grandparents, technical trades, spiritual inclinations, superstitions and electronics, its colour is brown and gem is cat's eye. Ketu is always in the opposite sign to Rahu, i.e., exactly 180 degrees away. Ketu also takes approximately 1-1/2 years to travel a sign and hence completes the round of the zodiac in 18 years.