# The Julian Calendar

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```					  The Julian Calendar
By: Casey Gilbert
What is the Julian Calendar
   “Julian Calendar n : the solar calendar
introduced in Rome in 46 b.c. by Julius
Caesar and slightly modified by Augustus,
establishing the 12-month year of 365 days
with each 4th year having 366 days and the
months having 31 or 30 days except for
February.”
What is the Julian Calendar?

 Each day is numbered consecutively from
January 1, 45 BC.
 A way of syncing the calendar
months and the seasons.
Who developed the Julian Calendar?
   The Julian Calendar was originally
developed by Julius Caesar and later
modified by his nephew, Augustus
Caesar.
When and Where did the Julian Calendar
Originate?

 The Julian Calendar system began in 46
BC and continued until 1582.
 The calendar was responsible for for time-
keeping in Rome.
Why was the Julian Calendar
initiated?
 (Before the Julian Calendar) Political
forces in Rome extended months to keep
favored politicians in office.
 The government essentially controlled
time in Rome.
 Julian Calendar helped to regain order
and to end the abuse of time that was
taking place in Rome.
Why did we stop using the Julian
Calendar?
 The tropical year of the Julian Calendar is
approximately 365 ¼, causing an error of
1 day every 128 years
 Threw off method of calculating Easter.
   ( Average Julian year was slightly too long,
causing Easter to fall a little earlier every
year).
What Calendar replaced the Julian
Calendar?
   The Gregorian Calendar replaced
the Julian Calendar in the 1500’s.
 Greece and Russia used the Julian Calendar
until the 1900’s and the Orthodox Church in
Russia still uses the Julian Calendar.
 “Gregorian Calendar (The Christian
Calendar) is based on the motion of the earth
around the sun.”
 We use the Gregorian Calendar today.
How do we calculate Julian
Calendar days?
   a = (14-month)/12
y = year+4800-a
m = month + 12*a - 3

 JD = day + (153*m+2)/5 + y*365 + y/4 -
32083
 Julian Date Converter!!!!
Sources
   http://www.skeptics.com.au/journal/1995/1_calendar.htm#Julian
   http://www.polysyllabic.com/Julian.html
   http://dictionary.reference.com/search?q=julian%20calendar