From an old word meaning "wanderer", the planets are those heavenly bodies that seem to move through the zodiac (science says planets are massive bodies in our solar system that revolve in orbits around the Sun, so giving this impression to us earthlings). Those that do not move perceptibly are known as the Fixed Stars (even though they do move imperceptibly over vast periods of time). In astrology, the planets include the Sun, the Moon and the Moon's Nodes (Dragon's Head and Tail). These are the main focal points for the cosmic energies that affect us. More on Planets.

A committee of modern astronomers has recently redefined the term "planet" to mean "any body massive enough to be round that is not a star but is orbiting one". They demoted Pluto (and promoted Ceres) to the status of "dwarf planet" in 2006. Pluto has also since (2008) been redefined as a "plutoid", a trans-Neptunian object (TNO) or Kyber Belt Object (KBO). These new definitions are generally irrelevant to astrology.