Happy Leap Day! Brought to you by Julius Caesar
Happy Leap Day! Brought to you by Julius Caesar February 29 means it's a leap year. (Nikolaeva Elena/iStock/British Library)
Happy Leap Day! Brought to you by Julius Caesar
Lexile: 1150L

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Every four years, February 29 appears on the calendar like a distant relative dropping in for a visit: it's regular enough to be expected, but just infrequently enough that it's often a surprise. However, leap days play an important role in keeping our calendars on track, and it's all thanks to Julius Caesar.

Most years, the calendar is made up of 365 days. However, the Earth's orbit around the sun is actually slightly longer than that, about 365 1/4 days-making the calendar year slightly shorter than a solar year. Which, if you're trying to establish an accurate system for measuring the passage of time and changing seasons, throws a small wrench in the works, Deanna Conners writes for EarthSky.org.

Julius Caesar was confronted with this dilemma back in 46 B.C.E., when he was developing what came to be known as the Julian Calendar. On the advice of an Alexandrian astronomer named Sosigenes, Caesar decreed that every four years an extra day would be added to the calendar to keep it on track, Conners writes. That way, the calendar would make up for the discrepancy and account for the slightly awkward length of the solar year.

At first, Caesar's solution seems simple and straightforward: "bank" those extra quarter-days for a few years, then spend them on a leap day. But as the centuries rolled on, people began to notice something was off. The Julian Calendar, which had been adopted throughout the former Roman Empire, was speeding ahead of the solar year. By the end of the 16th century, the calendar year had drifted as much as 10 days ahead, CNN reports.

The problem? The solar year is actually slightly shorter than Caesar and Sosigenes thought.

"It's not exactly a quarter of an extra day; it's a little less," physicist Judah Levine tells Rachel Wise for Quartz. "And so adding one day every four years was too much."

To be fair to Caesar and Sosigenes, they were only off by a matter of a few decimal points-astronomers now know that a solar year is actually 365.24219 days long. But while it may not seem like much, under the Julian Calendar, that slight error led to a discrepancy of about 11 minutes a year, Wise writes. So in 1582, Pope Gregory decided to reset the calendar and take those calculations into account with something called "the century rule."

"If a leap year falls on a century, a year ending in double zeroes, you only add a leap day if it's divisible by 400," Levine tells Wise. "For that reason 1900 wasn't a leap year but 2000 was."

Pope Gregory was also responsible for setting leap day as February 29, instead of adding it on to the end of the year. The calendar won't skip another leap year until 2100, but that little adjustment has kept our calendars fairly accurate for over 400 years.

Source URL: https://www.tweentribune.com/article/teen/happy-leap-day-brought-you-julius-caesar/

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Have you ever celebrated Leap Day before? How did you celebrate?
Write your answers in the comments section below

  • KaylaM-did
    4/06/2020 - 08:09 a.m.

    I never celebrated Leap Day before. I did however celebrated someone's birthday on Leap Day.

  • SierraL-did
    4/06/2020 - 08:14 a.m.

    No, I’ve never celebrated leap day. I don’t really think too hard about it like that.

  • DariusD-did
    4/06/2020 - 08:14 a.m.

    No, we haven't what is there to celebrate on a lep year, honestly it serves no purpose at all to celebrate; usually just adding more days in the month of Febuary

  • TalishaP-did
    4/06/2020 - 08:15 a.m.

    I never celebrated Leap Day. I didn't really pay attention to Leap Day.

  • JoshuaB-did
    4/06/2020 - 08:16 a.m.

    No. I've personally never celebrated a leap year.

  • RashellD-did
    4/06/2020 - 08:17 a.m.

    Yes I have celebrated leap day before. I only have celebrated this because my younger cousin she was actually born in February 29th which makes her supposed to be a very young age but when the leap day doesn’t happen she celebrated it the day before or after. This is only because so she won’t miss a birthday. Also, my father side of the family are very religious people and what the Bible says about the leap day they follow so the times I was spending with my father awhile back. They would really have like a gathering for just that day which to me was weird because it’s just an extra day meaning nothing but to others it’s something much more. Which is why it’s just like a normal day to me and to others it’s very sentimental based on what they’ve grown up knowing I believe.

  • JoshuaR-did
    4/06/2020 - 08:24 a.m.

    I have never celebrated Leap Day before. I never celebrated it because it would not be your "typical" holiday. So, for me to announce I am having a party for Leap Day, many people would look at me in an odd manner because it is not the typical thing to do. Furthermore, it just seems like an odd reason to celebrate. Yes, it is important to keep the calendar on par with the earth's rotation and keep the days in check, but besides that, there is nothing significant about this day. It is also not publicized by the media to celebrate, which is another reason I personally do not celebrate. So, despite Julius Caesar coming up with a bright idea to account for the solar year, it was slightly off which caused them to eventually be off by 10 days. This caused discrepencies which made Pope Gregory make a new calendar in 1582

  • ZionS-did
    4/06/2020 - 08:25 a.m.

    No, I have never celebrated Leap Day before, and I don't care about it as a "Holiday". I do think it's interesting how there is a system to compensate for the 365 1/4 year time frame. I don't celebrate any holidays to my knowledge, and I don't even bother looking at the calendar to see when Leap Day is going to occur.

  • EvanB-did
    4/06/2020 - 08:25 a.m.

    No, I haven’t because I have no reason to it’s not a regular day but it’s still not a really a holiday to me either.

  • JoseG-did
    4/06/2020 - 08:34 a.m.

    I never have celebrated Leap Day. I find the creation of the extra day interesting but I do not celebrate it.

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