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month





A period of time connected with the motion of the Moon around Earth. The familiar calendar (or civil) month is an artificial unit consisting of a whole number of days. For astronomical purposes there are several other types of month.
  • Synodic month or lunar month
       The average interval from one new Moon to the next – 29.53059 days

  • Anomalistic month
       The interval in which the Moon passes from perigee to perigee – 27.55464 days

  • Sidereal month
       The interval in which the Moon passes from a fixed position with respect to the stars back to the
       same position – 27.32166 days

  • Draconic month or nodal month
       The interval between successive passages of the Moon through its ascending node

  • Tropical month
       The interval between successive passages of the Moon through the vernal equinox – a mean
       of 27.21222 days

Related categories

   • CELESTIAL MECHANICS
   • UNITS