5/30/2023 0 Comments Was 2020 a leap year![]() ![]() (It replaced the old Julian Calendar by Julius Caesar that only has one rule of a leap year every 4th year, and is now about 13 days behind our current date. These leap year rules were introduced in 1582 by the Gregorian Calendar, named after Pope Gregory XIII. (It is not necessary to check the third condition) Will 2018 be leap year 2018 is not divisible 4 ( 504.5), so it will not be a leap year (it is not necessary to check the next two conditions). So it could be a leap year 2020 is not divisible by 100 ( 20.2), so it will be a leap year. So this keeps us pretty close, and any other adjustments can be done way in the future (when the Earth may be rotating a little slower, anyway!) Will 2020 be a leap year 2020 is divisible 4 ( 505). How far away each year is from the averageĮxample: look just before 2100, the worst year is 1.2 days ahead, but because 2100 is not a leap year they all get adjusted back by 1 day. This gets us 365.2425 days per year (1 day regained every 400 years = 0.0025 days per year), which is close enough to 365.242375 not to matter much. So another rule says that every 400 years is a leap year again. So every 100 years we don't have a leap year, and that gets us 365.24 days per year (1 day less in 100 year = -0.01 days per year). This is fairly close, but is wrong by about 1 day every 100 years. So every 4th year we add an extra day (the 29th of February), which makes 365.25 days a year. so something has to be done to "catch up" the extra 0.242375 days a year. Leap Years are any year that can be exactly divided by 4 (such as 2016, 2020, 2024, etc)Įxcept if it can be exactly divided by 100, then it isn't (such as 2100, 2200, etc)Įxcept if it can be exactly divided by 400, then it is (such as 2000, 2400)īecause the Earth rotates about 365.242375 times a year. etcĪ Leap Year has 366 days (the extra day is the 29th of February). ![]()
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