The Gregorian calendar has divided the months into 12 dividing the 365 days into either 30, 31, or 28 days. The months in order are January (31 days), February (28 or 29 days), March (31 days), April (30 days), May (31 days), June (30 days), July (31 days), August (31 days), September (30 days), October (31 days), November (30 days) and December (31 days).
The division of these months is as per the circulation of the earth around the sun. One complete year means one whole round of earth. There is a quarter of a day left for each year which makes leaves the time in each year and after four years the day is added into February as the 29th one thus called a leap year.
What are the types of calendars?
There are three basic types of calendar
Lunar
This calendar depends upon the revolution of the moon around the earth. It takes around 29.53 days for a moon to complete its phase. The appearance of the moon is in phases and it takes one full appearance of the moon and then a gradual reduction to another full moon to complete a whole round.
In this way, the number of days in a lunar year is 354.37 which is shorter than the 365 days year.
The weather do not synchronize with the calendar which made the effectiveness of the calendar weaker over time and people adapted to new calendars. Presently only Muslims follow the lunar calendar but its effect on weather is not much because of the fact that places, where the calendar is widely used, are consistently hot and the conditions remain prevalent throughout.
Luni-Solar
This calendar is a combination of lunar and solar calendars. The months in this calendar are 12 but after every few years, there is an addition of a thirteenth month so that the timeline remains consistent with the weathers.
This calendar is also not widely used except in some cultures like Asian culture uses the Chinese calendar and the Jewish Culture has the Hebrew calendar.
Solar
The type of calendar being used the world over today is the solar calendar which is the length of the revolution of Earth around the sun. This calendar was an adaptation of the lunisolar calendar.
The Romans had divided their year into ten months starting from the month of March at the beginning of the spring season and ending in December. The year did not have the seventy days of winter.
Later two more months between December and March were added called January (Janus to Roman; two-faced God) and February (in Roman it is a festival of purification). The calendar still wasn’t accurate.
It was during the era of Julius Ceasar that there were some major reforms being made. He had a calendar that had January 1st as the beginning of the year when the sun set half an hour late. The months were in the order sequence of 30,31 or 29 days.
January, March, May, July, August, October, and December with 31 days. April, June, September, and November had 30 days. February had 28 days. After four years a day was added in February marking it a leap year with 366 days as of 29th February.