The Western calendar is a solar calendar that has been used in the Western world for centuries. It is based on the Earth's orbit around the Sun, and the year is divided into 12 months, each with a specific number of days.
The Western calendar is also known as the Gregorian calendar, after Pope Gregory XIII, who reformed the calendar in 1582. Before the Gregorian calendar was introduced, the Julian calendar was used, which was introduced by Julius Caesar in 46 BC.
The Julian calendar was based on a 365-day year, with an extra day added every four years (leap year) to account for the fact that the Earth's orbit around the Sun is not exactly 365 days long.
However, the Julian calendar was not perfectly accurate, and it gradually drifted out of sync with the seasons. By the 16th century, the calendar was off by 10 days, which meant that the spring equinox was occurring on March 11 instead of March 21.
In 1582, Pope Gregory XIII introduced a revised calendar that corrected for this drift. The Gregorian calendar is based on a 365.2425-day year, with leap years every four years, except for years that are divisible by 100 but not by 400. This means that the year 2000 was a leap year, but the year 1900 was not.
The Gregorian calendar is the most widely used calendar in the world today, and it is the official calendar of most countries.
Here is a timeline of the key dates in the history of the Western calendar:
* 46 BC: Julius Caesar introduces the Julian calendar.
* 1582: Pope Gregory XIII introduces the Gregorian calendar.
* 1752: Great Britain and its American colonies adopt the Gregorian calendar.
* 1873: The Gregorian calendar is adopted by most Protestant countries.
* 1923: The Gregorian calendar is adopted by the Russian Orthodox Church.
* 1976: The Gregorian calendar is adopted by China.
* 1981: The Gregorian calendar is adopted by Ethiopia.
Today, the Gregorian calendar is the most widely used calendar in the world, and it is the official calendar of most countries.