Emperor and pope gave us leap year
Leap day is the perfect time to get airborne.
February 29th, 2012
12:38 PM ET

Emperor and pope gave us leap year

It's leap day, a once-every-four-years bonus you can thank Julius Caesar and Pope Gregory XIII for.

We add a day at the end of February every four years because it takes the Earth about 365.242 days to make a full orbit around the sun. So we take those .242 days, round 'em up slightly and present the world with February 29, an extra day of, well, work for me, campaigning for the GOP presidential hopefuls or, if you fancy yourself a CNN iReporter, leaping!

Open Story: Leap day around the world

We thank the Roman emperor Caesar and the 16th century pontiff for putting the day into place.

In 46 B.C., Caesar decreed that under the Julian calendar, a day would be added in any year evenly divisible by four. However, accounting for the rounding up, that got the Romans a little ahead of themselves as far as time goes,  according to no less of an authority on things involving watches and calendars than timeanddate.com.

That little discrepancy, which amounted to 11 minutes every year, had added up to 10 whole days by 1582, when Pope Gregory said he had no time for inaccuracies and created the Gregorian calendar, under which we mark our days to this day. Gregory also designated February 29 as the official leap day and set up some rules so that we'd never end up 10 days ahead of ourselves again.

Here's how that works: Leap year occurs in every year that is evenly divisible by four and every century year that is divisible by 400. Hence, while 1200 and 2000 were leap years, 1700 and 1900 were not.

This also means that in the United States, leap years are presidential election years, which means we can always look forward to that extra day of campaigning.

Four million people born on leap day

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Filed under: Earth • History • Science
soundoff (67 Responses)
  1. HisbabyFACE

    JASON GRILL of Parkville Missouri for PRESIDENT !!! > HE gave you the "leapyear" RIGHT JASON?
    Like BABY BOY BRADLEY.... its a "leap of faith"

    February 29, 2012 at 12:55 pm | Report abuse |
  2. BOMBO ©

    This is all very interesting, but who is the chick in the picture?

    February 29, 2012 at 12:57 pm | Report abuse |
    • smartaz

      My wife just before she hit the ground after I threw her off the roof.

      February 29, 2012 at 1:43 pm | Report abuse |
    • beelzabarber

      a choir by that the church dressed up like a girl so as not to raise any eyebrows when he is seen with one of the priests

      February 29, 2012 at 1:47 pm | Report abuse |
    • BOMBO © confused, scratching his head

      Okay, my response to smartaz may have been considered in bad taste, but was it worse than the choir boy comment?

      February 29, 2012 at 2:32 pm | Report abuse |
    • banasy©

      They're good that way...

      February 29, 2012 at 4:38 pm | Report abuse |
  3. Derek James

    Caesar wasn't emperor. He was voted dictator. Augustus is traditionally seen as the first emperor.

    February 29, 2012 at 1:04 pm | Report abuse |
    • chinaman03

      i didn't know augustus was not ceasar. good lord!

      February 29, 2012 at 1:54 pm | Report abuse |
  4. Thegoodman

    Skilled scientists, mathematicians, and astronomers gave us Leap Year. The pope and Ceasar did nothing more than accept the knowledge from people smarter than themselves.

    February 29, 2012 at 1:18 pm | Report abuse |
    • humanbean

      Shhh...you know how dictators and christians like to cherry pick and steal from everyone else and spin it with originality

      February 29, 2012 at 3:40 pm | Report abuse |
    • banasy©

      Don’t know about the Pope, but that Julius Caesar was quite the dummy, wasn’t he?

      February 29, 2012 at 5:34 pm | Report abuse |
  5. fat cat

    Betya, the author is looking forward to 2100 when she does not need to campaign for anyone since it's not a leap year and there is no prez election. We cats do will elect caz in 2100.

    February 29, 2012 at 1:28 pm | Report abuse |
    • Paul Price

      2100 will not be a leap year, but will be a presidential election year.

      February 29, 2012 at 3:16 pm | Report abuse |
  6. barone

    Julius Caesar was never Emperor. Come on CNN, these mistakes make you look lazy.

    February 29, 2012 at 1:29 pm | Report abuse |
    • Nah

      That's because CNN, like most every moron in the world, believe what they believe not because they're apprised of the facts, but because they heard someone, somewhere, sort of say something like what they believe.

      February 29, 2012 at 3:30 pm | Report abuse |
  7. NJ

    Why do non-Christians use the Christian calendar? Go use your own.... especially Atheists!!

    You know why Pope Gregory picked to be year 2012........................

    February 29, 2012 at 1:33 pm | Report abuse |
    • delectapix

      Iit's not a christian calendar, Caesar predates Christianity and the Pope G slightly modified the Julian calendar. The Julian calendar is based on a solar year. Why don't Christians stop hijacking the movements of celestial bodies!

      February 29, 2012 at 1:41 pm | Report abuse |
    • Jonathan L

      Pope Gregory picked year 0 to be approx. Jesus Christ' birth.
      So it was around 2012 years ago when Christ was born.

      February 29, 2012 at 1:45 pm | Report abuse |
    • Cedar Rapids

      Why do christians use the norse and roman gods for days of the week and months?
      go use your own.

      February 29, 2012 at 1:50 pm | Report abuse |
    • I give up

      Why does anybody ever do anything. What's the point.

      February 29, 2012 at 1:52 pm | Report abuse |
    • SJ

      Before the 20th century, christians never believed that the earth revolved around the sun. How could they have given us the Julian Calander.

      February 29, 2012 at 1:55 pm | Report abuse |
    • jsf12

      In reply to Jonathan L, there was no year 0. In Cristian numbering of years, the year before 1 AD was 1 BC.
      Pope Gregory did not change the numbering of the years, so he did not select the base year nor create the estimate of how many years ago Jesus was born. Emperor Constantine did all that (selected the number of the then current year, implicitly setting the year in which Jesus was assumed to have been born). Constantine also selected Dec 25 as the birth date of Jesus.

      February 29, 2012 at 2:28 pm | Report abuse |
    • humanbean

      Probably similar to the reason that Christians celebrate Mithra's, I mean Jesus's birthday on December 25th

      February 29, 2012 at 3:51 pm | Report abuse |
    • banasy©

      ind of Druid dude, lifting the veil...

      February 29, 2012 at 4:49 pm | Report abuse |
    • hypocrisy bureacracy

      Yet another example of Christians making an exclusive club for themselves in spite of their their savior's inclusive teachings.

      February 29, 2012 at 8:46 pm | Report abuse |
  8. King of the Popes

    While the rest of you have been plotting and loving one another, I have become King of the Popes.

    February 29, 2012 at 1:41 pm | Report abuse |
  9. milan

    And by this calculation from very "smart" Pope, smarter than Galileo Galilee (who found that earth is spinning around 70 years after "smart" Pope) Catholic church implemented that Christmas is on December 26th not January 7th, again "accidentally" that day is biggest and holiest PAGAN holiday SUN GOD. Beside changing Christmas to this day Catholic church after great schism on year 1054 changed altars to the west instead keep east. "accidentally" after year 1054 all churches burned except one in roman empire and after they rebuild them they turned altars to the west. What i am trying to say is that Catholic church is pagan church returned under Catholic Christianity and did a greatest sin of Christianity which is prohibited by old way or Orthodox way which is, you can not force someone to be christian it is by good will. ALL crusades started after year 1054 and they were done by Catholic church to take over Orthodox Christians. Last known and recorded Crusade from Catholic Church was ww2 and Hitler.Catholic Pope in the year 1931 sent a letter to Hitler which states"On your Holly war you must remember to protect Catholics and you have full support on attacking orthodox Russia".

    February 29, 2012 at 1:41 pm | Report abuse |
    • James

      where did you get your facts, another CNN article?
      1.Christmas is celebrated on the 25th (but I'm sure you knew that)
      2.Pagen religions focus on multiple dieties (polytheism as opposed to Christian monotheism)
      3.The Crusades happend because the seljuk turks forbaid pilgramage to Jerusalem
      4.WWII had nothing to do with religeon

      February 29, 2012 at 2:02 pm | Report abuse |
    • BOMBO ©

      James, I salute you. You got much further through that disjointed rant than I was able to.

      February 29, 2012 at 2:08 pm | Report abuse |
    • Hector Gonzalez

      Let me quess???? Protestant no denomination "Christian" a la carte??

      February 29, 2012 at 3:55 pm | Report abuse |
    • banasy©

      Keep searching for meaning. milan.

      February 29, 2012 at 4:51 pm | Report abuse |
    • milan

      JAMES
      1. My bad and typing error ,,Dec 25. Very smart reply of yours
      2. Pagan is polytheism but altars on the west celebrates other Pagan god and there are much more god under
      Catholic saints and dates that i can't teach you all in one comment on CNN. But i only named Dec 25 which is on the same date as Christmas. But not everybody can get that.
      3. Crusade on Jerusalem was the first one, bit there was more of them not just SELJUK TURKS. Stop reading Wikipedia as your knowledge educator.
      4. WW2 had nothing with religion. I know that you couldn't find anything about it on WIKIPEDIA but people that went to higher schools than High school and if they studied History know what i am talking about, in your case, keep reading WIKI but please do not reply to science and history, just sports.

      February 29, 2012 at 6:13 pm | Report abuse |
    • milan

      BANASY

      I already did, as i am Historian, mainly religion history of the world, in this case just pointed out the tip of the world history of the churches. Real knowledge is in the books not YOUTUBE. You can find those in the Library, that is usually big old building in every city, in your city it might be next to electronics and Iphone stores. You can search it on google map on your phone. Try it, it is hard but it will help you to get some knowledge and than you can reply to some, i say some comments.

      February 29, 2012 at 6:28 pm | Report abuse |
    • James

      @Milan Just between me and you I know there were more crusade, I was just hoping you didn't know that. in fact it wasn't untill the third with Saladin that they fought for pilgramage. The first was about the Byzantiens crying to the pope about the turks. I get what your saying about the Catholic stuff (patron saints right?). I'm open to learning, how was WWII related to religion?

      March 1, 2012 at 12:27 pm | Report abuse |
    • James

      Oh and P.S., If your some "hot shot" historian, why do you feel the need to brag about it? Sure we can assume your stupid, but if you "prove" your not then we'll think your even more stupid.

      March 1, 2012 at 12:29 pm | Report abuse |
  10. bilbowall

    Yes...thanks to those of us who know Caesar wasn't an emperor, just an appointed dictator. Augustus was the first appointed Emperor of the Roman Empire and considered the greatest for all his initial accomplishments.

    February 29, 2012 at 1:53 pm | Report abuse |
  11. mike in dallas

    something needs to be done to correct this error

    February 29, 2012 at 2:02 pm | Report abuse |
    • BOMBO ©

      Let's increase the speed of Earth's orbit around the sun.

      February 29, 2012 at 3:57 pm | Report abuse |
  12. Jj

    All hail Caesar!

    February 29, 2012 at 2:05 pm | Report abuse |
  13. jsiller

    those damn illuminati! it is a conspiracy!

    February 29, 2012 at 3:06 pm | Report abuse |
    • banasy©

      Run for your lives......aaaaaaaaaaaaaaaaaaaargh!

      February 29, 2012 at 4:53 pm | Report abuse |
  14. Tim from Maryland

    That's not exactly the rule. It's not that leap year occurs in every year divisible by 4 and every century year divisible by 400. 1900, for example, is divisible by 4, but it was not a leap year.

    Here's how it works. Leap year occurs in every year divisible, with this exception:
    If the year is divisible by 100, no leap year, with this exception:
    If the year is divisible by 400, leap year.

    February 29, 2012 at 3:37 pm | Report abuse |
    • banasy©

      ....or every ears to the day from the last leap day.

      February 29, 2012 at 4:54 pm | Report abuse |
  15. E N

    What if some one was born on the 29th of February?

    February 29, 2012 at 3:50 pm | Report abuse |
    • BOMBO ©

      They only age one quarter as quickly.

      February 29, 2012 at 4:06 pm | Report abuse |
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