Graha (from Sanskrit Grah graha-seizing, laying hold of, holding is a 'cosmic influencer' on the living beings of mother Bhumidevi (Earth). In Hindu astrology, the Navagraha (Sanskrit: Navgrah, nine seizers or nine influencers) are some of these major influencers. All the navagraha have relative movement with respect to the background of fixed stars in the zodiac. This includes the planets: Mars, Mercury, Jupiter, Venus, and Saturn, the Sun, the Moon, as well as positions in the sky, Rahu (north or ascending lunar node) and Ketu (south or descending lunar node). According to some, Grahas are the "markers of influence" that point out the karmic influence on the behavior of living beings. They themselves are not causative elements but can be compared to traffic signs. According to the astrological treatise Prasna Marga, there are many other spiritual entities called grahas or spirits. All (except the navagrahas) are said to have been born of the anger of Lord Shiva or Rudra. Most grahas are generally malefic in nature but there are a few that may be good. The book called The Puranic Encyclopedia, under the heading 'Graha Pinda', gives a list of such grahas (spirits or spiritual entities, etc.), that are said to afflict children, etc. Also in the same book in various places the names of spirits (grahas) are given, like 'Skhanda graha' that is said to cause miscarriage.