The Gregorian calendar

This calendar is also known as the western calendar or Christian calendar. This calendar was introduced by Pope Gregory XIII in February 1582 but the design was adopted from a design by an Italian doctor, astronomer and philosopher Luigi Lilio (also known as Aloysius Lilius). This doctor was born in 1510 and unfortunately died in 1576, six years before his design was adopted. The Gregorian calendar was first adopted in Italy, Poland, Portugal and Spain in 1582.

The Gregorian calendar is a solar calendar. This calendar regular year consists of 365 days, which is divided into 12 months of irregular lengths. Each of this month’s consist either 30 or 31 days with 1 month consisting of 28 days during the common year. A leap year occurs every 4 years to add an extra day to the second month February making it 29 days.

The calendar has also been subjected to the following changes:

1.      In October 1582, 10 days were dropped.

2.      New rules were set to determine the date of Easter.

3.      The rule for calculating leap year was changes to include that a year is a leaf year if:

a.      The year is evenly divisible by 4

b.      It is not a leap year, if the year can evenly be divided by 100 unless;

c.       The year is also evenly divisible by 400, and then it is a leap year.