History Calendar

Gregorian calendar calculations based on the Earth's rotation (rotation of the earth on its axis) and the revolution of the earth (the earth orbit around the sun). According to the system Yustisian 1 year = 365.25 days and a count of unity (the first year AD) started at the birth of Jesus according to the Christian faith. Basic calculations according Yustisian system are: first, the rotation of the earth is called a day = 24 hours and the second revolution of the earth called one year = 365.25 days. Based on these calculations, the Roman emperor in 47 BC set a calendar with the following provisions:

One year old with an excess of 365 days 6 hours each year Every four years or so the number is divisible by 4 to 366 days old called leap year (year-long), while the ordinary (non-leap year or short year) 365 days old. How to set one if the year is divisible by 4 is a leap year mean. In 1995 for example: 4 = 498.7 is not a leap year, while 1996: 4 = 499 is a leap year. Subsequent developments in the 16th century there was a shift from the usual spring which usually falls on March 21, has come a long way, then do a correction. Where prior to the calculation of one year is 365.25 days then since then one year to 365.2425 days. It was based on the calculation that the revolution of the Earth is not 365 days 6 hours but exactly 365 days 5 hours 56 minutes or 365 days 6 hours less than 4 minutes.

Therefore, on March 21, 1582 there was a shift to early spring fall more advanced in Europe. For the correction due to rounding 4 minutes during the 15 century the Pope Gregory XIII set as follows:

Pliers every year divisible by 100 though which is divisible by 4 is a leap year earlier provisions no longer a leap year. It is due to rounding of the day for leap year every 4 years that preceded a few minutes of real, then held again rounding on every 100 years.

Held once every 400 years rounding one day, so even if divisible by 100 then it remains a leap year. Calculation basis is the excess of 4 hours a year then the year 400 to 1600 minutes = 26 hours 40 minutes.

To remove the excess of rounding that has gone before it was cut days, ie after the date of October 4, 1582, being the date immediately following the October 15, 1582. so on 5 - October 14, 1582 (for 10 days) does not exist in the AD calendar.

With the correction of the calculation basis since 1600 to 2000 there was a correction that is 3 times in 1700, 1800 and 1900. This is because according to the conditions before the year 1582 every year divisible by 4 is a leap year. But since 1582 a new provision that applies every year divisible by 100 is not a leap year except for years divisible by 400. Thus in 1600 and 2000 remains a leap year because it is divisible by 400. the year is divisible by 4 is not a leap year for the period after 2000 is 2010, 2200, 2300 in 2400 while still a leap year because it is divisible by 400.

The conclusion that can be found on the trip of the year AD 1-2000 are:

year 1-1582 all years divisible by 4 is a leap year

on 5 - October 15, 1582 did not exist in the calendar calendar

In 1700, 1800, 1900 is not a leap year (3 years 3 days for correction)

Cycle of the solar year is a 4-year cycle for small (4 X 365) + 1 = 1461 days, while the magnitude of the cycle every 400 years (100 X 1461) - 3 = 146 097. February in normal (non-leap) were aged 28 days in a leap year 29 days old. Moon is 31 days old in January, March, May, July, August, October and December. Months 30 days old is the month of April, June, September and November.