Felix Bisextilis!

It is Leap Year Day.  In Latin this is bisextilis.

For this intercalary day in the Roman Martyology we find this:

leap year

When there isn’t a 29 February, the saints are observed on 28 February.

In 46 BC, on the advice of the Alexandrian astronomer Sosigenes, G. Iulius Caesar created a calendar system that added one day every four years to make up for the fact that the Earth’s year is slightly more than 365 days. The Earth circle the Sun in slightly more time than it takes for the Earth to rotate 365 times (365.24219). Calendar years with 365 drift from the actual year by about 1 day every 4 years.  After a while the month named after Caesar, July occur during the winter (in the Northern hemisphere).

Caesar’s Julian Calendar was maintained until 1582 when Pope Gregory XIII determined that in his Gregorian Calendar leap days would not occur in years ending in OO, unless the year is divisible by 400.

Felix Bisextilis!

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About Fr. John Zuhlsdorf

Fr. Z is the guy who runs this blog. o{]:¬)
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16 Responses to Felix Bisextilis!

  1. Mark of the Vine says:

    Is the fact that a leap year cannot occur during years ending in 00 purely arbitrary?

  2. bookworm says:

    I wouldn’t describe it as “arbitrary.” It’s designed to eliminate 3 leap years out of every 400 years, because that would be a little too many and throw the calendar off somewhat. Note, however, that this rule does NOT apply if the “00” year is divisible by 400… hence, 2000 was a leap year.

  3. Andrew says:

    Interesting! Also, I presume that “bisextilis” comes from “bis-sextus” = twice the sixth, with the idea that the sixth day is repeated. But I wonder: why “twice the sixth” since the additional day could have fallen on any other day of the week?

  4. Pingback: Happy Leap Day! « The Port Stands At Your Elbow

  5. Wendy says:

    Because sextilis was six days before the kalends (1st) of March (inclusive) or 24 February. The intercalary month that the Romans used to try to keep the civil calendar in sync with the tropical calendar was inserted behind one of their major festivals on the 23rd – when they remembered to do it. In the reform of the calendar, one day was inserted behind the 23rd of February every three or four years, and was considered the “double sixth day” or bis sextilis. Bis sextilis and sextilis (the 24th and 25th to us) were considered as one day [one very long day…].

    The feast of St. Matthias in the old calendar fell on the 24th of February in common years, but in leap years, because of bis sextilis, it was celebrated on the 25th.

  6. jarhead462 says:

    I will watch the “Take a Leap” episode of Frasier tonight, where he sings (and forgets the lyrics to) Buttons and Bows. – one of the funniest moments ever. Hopefully, it will take my mind off of my Ember Day fast ;)

    Semper Fi!

  7. wmeyer says:

    Mark: It’s about adjusting the calendar for accuracy. Years divisible by 100 are not leap years, but years divisible by 400 are.

  8. irishgirl says:

    ‘Bisextilis’-hmmm, leave it to the Latin language to give a cool name to Leap Year! Never heard this word….
    Ah, the things we learn here-thanks for this, Father Z!

  9. oakdiocesegirl says:

    What should be pointed out to the rest of the world at large, is that without the acts of a Roman Catholic Pope, the world would not even be able to TELL TIME correctly! So much for our Church being irrelevant in the public square!

  10. Tina in Ashburn says:

    My crazy, hilarious, practical jokester father [RIP] somehow got himself baptized on February 29, in Manila back in the 50s when he converted from his Christian denomination. It was a family joke that it was just like dad to go and do something so important, on a day commemorated every four years.

  11. Geoffrey says:

    “I will watch the ‘Take a Leap’ episode of Frasier tonight, where he sings (and forgets the lyrics to) Buttons and Bows.”

    Now I am going to have that song in my head all day!

  12. uptoncp says:

    When was the kalendar changed, and the leap day moved from vi. Kal. Mar. to the 29th?

    Incidentally, when S. Matthias was moved to the 25th in leap year, his vigil, naturally, moved with him to the 24th, thus disentangling it from any feasts occurring on the 23rd.

  13. hald says:

    When the Gregorian calendar was adopted throughout the Catholic world in 1582, Thursday, 4 October 1582 was followed by Friday, 15 October 1582, skipping 10 days. The British empire did not follow suit, until 1752, when Wednesday, 2 September 1752 was followed by Thurdsay, 14 September, 1752, skipping 11 days. Note that the American Revolution followed a mere 24 years later. Other nations, notably Russia did not follow suit until 1918 where Wednesday, 31 January 1918 was followed by Thursday, 14 February 1918, skipping 13 days. Greece was the last European country to adopt the new calendar when Wednesday, 15 February 1923 was followed by Thursday, 1 March 1923, also skipping 13 days.

  14. Precentrix says:

    I seem to recall randomly that St. Teresa of Avila died on the day that the calendar was changed (not sure where, though… and presumably it would either be the day before or the day after, if you see what I mean).

  15. Hieronymus in Canada says:

    Precentrix: she died the day before it was changed, and thus was buried nominally a couple of weeks later, though only a day or two had elapsed.

  16. Mark of the Vine says:

    I always wondered where our name for leap year (“ano bissexto”) came from. Thanks for the info!