All measurements of time have historically depended on astronomical observations - the day is measured from the rotation earth on its axis, the week approximates the changing phases of the Moon, the month is measured from the revolution of the Moon around earth and the year is measured from the revolution of earth around the Sun. Unfortunately earth or moon do not complete their cycle in full no of days. Moon's cycle 29.53059 days and earth's orbit around sun takes 365.242196 days. So 12 months are short of a year, and 13 months are longer. In this lesson we describe here the history and detailing of the commonly used Gregorian Calendar along with the different lunar calendars used in India.
Gregorian Calendar : The Gregorian Calendar was first introduced by Julian Calendar. It was based on 365.25 days. The year was divided in twelve months, of which eleven contained 30 or 31 days and the 12th had 28 days only. The first month was March and the last month was February. July is named after Julius Caesar and August after Augustus Caesar, both months being allocated the full 31 days, as belittled a Caesar. The seventh month was September, the eight October, the ninth November the tenth December, after the Latin Septem, Octo, Novem and Decem for seven, eight, nine & ten respectively. To account for quarter day, every fourth year the last month February was a leap year. February contained 29 days. However this calendar was fast by over 11 Minutes every year and by 1500 the error amounted to approximately 11 days. To correct the calendar, Pope Gregory ordered that October 15,1582 should follow October 4. The new Calendar also moved the beginning of the year from March 25 to January 1. February now did not have a leap year in centuries unless perfectly divisible by 400. Thus came the present Gregorian Calendar into existence. According to the present Gregorian Calendar average year is 365.2425 days which is more than the actual by .000304 days, that is, 26 seconds. This can be ac counted for, if we again have February of 28 days after 3200 years. However, this is not yet accounted in the Gregorian calendar.
Gregorian Calendar : The Gregorian Calendar was first introduced by Julian Calendar. It was based on 365.25 days. The year was divided in twelve months, of which eleven contained 30 or 31 days and the 12th had 28 days only. The first month was March and the last month was February. July is named after Julius Caesar and August after Augustus Caesar, both months being allocated the full 31 days, as belittled a Caesar. The seventh month was September, the eight October, the ninth November the tenth December, after the Latin Septem, Octo, Novem and Decem for seven, eight, nine & ten respectively. To account for quarter day, every fourth year the last month February was a leap year. February contained 29 days. However this calendar was fast by over 11 Minutes every year and by 1500 the error amounted to approximately 11 days. To correct the calendar, Pope Gregory ordered that October 15,1582 should follow October 4. The new Calendar also moved the beginning of the year from March 25 to January 1. February now did not have a leap year in centuries unless perfectly divisible by 400. Thus came the present Gregorian Calendar into existence. According to the present Gregorian Calendar average year is 365.2425 days which is more than the actual by .000304 days, that is, 26 seconds. This can be ac counted for, if we again have February of 28 days after 3200 years. However, this is not yet accounted in the Gregorian calendar.
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