Space Astronomy


  • Planet means wanderer in ancient Greek
  • A solid (or partially liquid) body orbiting a star
  • Too small to generate energy by nuclear reactions
  • Rocky debris leftover from the creation of a star
  • Has enough mass for its self-gravity to have reached hydrostatic equilibrium
  • It has cleared its neighbourhood
    • Managed to clear orbit of any debris


  • Form as part of star formation process