section_path: Intercalation/Julian calendar
section_name: Julian calendar
paragraph_text: Julian calendar
  
  In the Julian calendar, the average (mean) length of a year is 365.25 days. In a non-leap year, there are 365 days, in a leap year there are 366 days. A leap year occurs every fourth year during which a leap day is intercalated into the month of February. The name "Leap Day" is applied to the added day.
  
  In astronomy, the Julian year is a unit of time defined as 365.25 days, each of exactly 86,400 seconds (SI base unit), totaling exactly 31,557,600 seconds in the Julian astronomical year.