The history of the rules is rather involved. These three rules are trying to keep the seasons near fixed dates on the calendar, with the first day of spring (the vernal equinox) near March 21.Īlthough other rules have been proposed in attempts to improve on the rules of 1582, none has been adopted for civil purposes. If divisible evenly by 400, a Gregorian year is a leap year so the year 2000 is a leap year.If divisible evenly by 100, a Gregorian year is a normal year with 365 days (e.g.1900/100=19, so 1900 is a normal year of 365 days as is 2100), UNLESS.If divisible evenly by 4, a Gregorian year is a leap year, with a February 29 and 366 days (e.g.However, only a handful of countries had adopted the Gregorian calendar then, and the rest of the world was still using the Julian calendar. Of course, the same can be said about the year 1600. The Gregorian calendar's rules for leap years have three parts: The number 2000 is evenly divisible by 400, so it was a leap year even though it can also be evenly divided by 100. "An Act for regulating the Commencement of the Year, and for correcting the Calendar now in use"įirst introduced in 1582 by Pope Gregory XIII as a replacement for the Julian calendar, this calendar is now in worldwide use for civil purposes. The number 2000 is evenly divisible by 400, so it was a leap year even though it can also be evenly divided by 100. While this still doesn’t perfectly line up with the solar year, it will be 3,300 years before this calendar begins to diverge from our solar year by a day.The year 2000, like the years 19, is a leap year - with 29 days in February but the years 1900, 1999, 2001, 2002, 2003, 20 are not leap years - and have only 28 days in February.Ĭanada uses the "Gregorian" calendar through the heritage of the British Act of 1750: This makes the average year 365.2425 days long – much closer to the solar 365.2422-day year. Since 365.25 days, while close, is still longer than the 365.2422-day solar year, Pope Gregory XIII eventually created the Gregorian calendar that we currently follow in which a leap day is occassionally skipped. After this, he ordered a 365.25-day year with a leap day added every four years.īut even this change wasn’t good enough. The idea behind this decree was to all at once correct the damage that had already been done from years of drifting out of sync with the seasons. A leap year occurs on all years divisible by four (e.g., 2016, 2020, 2024, and so on). In 46 BC, Julius Caesar declared they would, for just one year, take on a 445-day calendar he called the Year of Confusion. Therefore, leap years have an extra day, February 29th. 2000is perfectly divisible by 400, So, it is a leap. But the Romans were still behind, trying to adjust their calendar by randomly adding days or months here and there. Century years are leap years if they are divisible by 400. The Egyptians eventually began observing a 365-day year with a leap-year system. The Egyptians who adopted this calendar attempted to solve that problem by adding an extra 5 days of festivals and partying at the end of the year. With just 360 days, this calendar was an entire week shorter than the Earth’s orbit around the sun. The ancient Sumerian calendar of 5,000 years ago very simply divided the year into 12 months with 30 days each. Throughout history, humans have dealt with the fact that the solar year doesn’t line up with our calendar in many different ways. see our handy chart above to help you easily determine when it’s a leap year! History of Leap Years 1600, 2000, etc.), then it actually is a leap year. However, if it is divisible by 100, but also divisible by 400 (i.e. For example, the years 1600, 2000, 2400, and 2800 are century leap years since those numbers are evenly divisible by 400, while 1700, 1800, 1900, 2100, 2200, 2300, 2500, 2600, 2700, 2900, and 3000 are common years despite being evenly divisible by 4. 1800, 1900, etc.), it is NOT a leap year. This means that years such as 1992, 1996 are leap years because they are divisible by 4 and are not affected by the rest of the rule which applies to century. To put it as simply as possible, if the year is also divisible by 100 (i.e. 2012, 2016, 2020, 2024, etc.), but there are some exceptions to this rule, which can get kind of confusing. We all know that leap years are the years that are divisible by 4 (i.e.
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