What is a leap year?
A leap year has 366 days in a year as opposed to the regular 365 days. The extra day is added to February, the shortest month of the year, as February 29.
Why was a leap year introduced?
- One year in a solar calendar reflects one revolution of the Earth around the Sun which generally we take to be 365 days.
- But in actual the Earth takes 365 days, 5 hours, 48 minutes and 46 seconds to revolve around the Sun.
- Now this extra time of about 6 hours is to be adjusted.
- Hence at the interval of four years (6*4=24 hrs) one extra day is added in the shortest month i.e. February.
- However, even this method was not error-free, because the six hours used for calculation are still different from the actual 5 hours, 48 minutes and 46 seconds, making the calendar year slightly longer than the solar year.
Does leap year come every four year?
- No. Because even the above method was not error-free, because the six hours used for calculation are still different from the actual 5 hours, 48 minutes and 46 seconds, making the calendar year slightly longer than the solar year.
- Thus, it was decided that some leap years — about one leap year every century — would be dropped to manage the extra day. The years chosen for this were those ending with 00.
- However, dropping the leap year from all years ending with 00 would again throw the calculation out of whack. Finally, in the Gregorian calendar, the 00 years that were divisible by 400 ended up as leap years. Thus, 1900 was not a leap year, but 2000 was.