Cycle is a term used for every uniformly-returning succession of the same events. On such successions or cycles of years rests all chronology, particularly the calendar. Our common solar year, determined by the periodical return of the sun to the same point in the ecliptic, everybody knows contains fifty-two weeks and one day, and leap-year a day more. Consequently in different years the same day of the year cannot fall upon the same day of the week. And as every fourth year is a leap-year, it will take twenty-eight years (4x7) before the days return to their former order according to the Julian calendar. Such a period is called a solar cycle. The cycle of the moon, or golden number, or Metonic cycle, is a period of nineteen years after which the new and full moons return on the same days of the month. Research Cycle
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Research Cycle