Live data from Hacker News

Did you ever wonder why December has 31 days? (1997)

projects.csail.mit.edu

21–30 of 70 posts

Re: Did you ever wonder why December has 31 days? (1997)

#21
post #18

The more interesting question to me has always been: Why are the months numbered wrong? Dec ember is month 12, nov ember is month 11, oct ober is month 10. There's an offset of 2 between the month name and the number it references.

Because the calendar used to start in March. Feb was truncated because it was the last month of the year, thus where to put all the fudge factor to make the year work right.

Re: Did you ever wonder why December has 31 days? (1997)

#22
post #21
post #18

The more interesting question to me has always been: Why are the months numbered wrong? Dec ember is month 12, nov ember is month 11, oct ober is month 10. There's an offset of 2 between the month name and the number it references.

Because the calendar used to start in March. Feb was truncated because it was the last month of the year, thus where to put all the fudge factor to make the year work right.

It's also worth noting that 'winter' used to be monthless in the Roman calendar, so there were 10 months, ending in December (so all of the number names make sense) and then a big blob of 'winter' before the new year started.

Re: Did you ever wonder why December has 31 days? (1997)

#23
post #5

This is a cute story, but it lacks all sources, and it contradicts Wikipedia [1] [2]: > Commonly repeated lore has it that August has 31 days because Augustus wanted his month to match the length of Julius Caesar's July, but this is an invention of the 13th century scholar Johannes de Sacrobosco. Sextilis in fact had 31 days before it was renamed, and it was not chosen for its length (see Julian calendar). According…

> March was the first, hence July and August were called quintilis and sextilis, for fifth and sixth, respectively

An even better example is the actual numbered months:

- Septum (7)

- Octo (8)

- Novem (9)

- Decem (10)

Re: Did you ever wonder why December has 31 days? (1997)

#24
post #18

The more interesting question to me has always been: Why are the months numbered wrong? Dec ember is month 12, nov ember is month 11, oct ober is month 10. There's an offset of 2 between the month name and the number it references.

March or Martius* was originally the first month and the year was only 10 months long

http://www.webexhibits.org/calendars/calendar-roman.html

https://en.wikipedia.org/wiki/Martius_(month)

Re: Did you ever wonder why December has 31 days? (1997)

#25
To see how/right wrong it is, you can actually look at the primary source material and see for yourself.

Here for example is an image of a pre Julian calendar http://en.wikipedia.org/wiki/File:Roman-calendar.png

Among other things, you can also see another bizarre truth: the pre Julian calendar did not have a leap day, it had a leap month (more or less randomly inserted sometimes to delay elections). It's labeled INTER on the image.

The terms NON and EIDVS are the Nones and Ides of each month the latter of which I imagine Julius would have liked to reform out of the calendar all together. Hindsight.

Which reminds me of a not so useful poem:

In March, July, October, May,

The Ides are on the fifteenth day,

The Nones the seventh; but all besides

Have two days less for Nones and Ides.

Re: Did you ever wonder why December has 31 days? (1997)

#26
post #9

True or not, it's finally given me the means to remember which months have how many days.

Interesting, I never thought of this problem before. In Thai, all month names are suffix with a word indicating number of days in a month. For example, "-khom" in "Mokkarakhom" (January) indicates 31 days, where "-yon" (e.g. Mesayon, "April") indicates 30 days. Benefit of being late-adopter allow us to name a month in a convenient way, I guess.

Re: Did you ever wonder why December has 31 days? (1997)

#27
post #13

For centuries in the western world, the Christian church, which considered this to be in its purview, kept trying different calendar schemes to try to make a set of months, preferably equal, fit neatly into the year. There have been may solutions tried or proposed, and the history of this has a certain puzzle-like fascination, but it's not clear to me why people cared so much about this. Astronomical periods are OK,…

> For centuries in the western world, the Christian church, which considered this to be in its purview, kept trying different calendar schemes to try to make a set of months, preferably equal, fit neatly into the year.

That's not really a fair description of adopting a pre-existing system and issuing a single patch after more than a millenium. Sure, lots of things have been discussed, but not much has actually been tried.

Re: Did you ever wonder why December has 31 days? (1997)

#28
post #19
post #13

For centuries in the western world, the Christian church, which considered this to be in its purview, kept trying different calendar schemes to try to make a set of months, preferably equal, fit neatly into the year. There have been may solutions tried or proposed, and the history of this has a certain puzzle-like fascination, but it's not clear to me why people cared so much about this. Astronomical periods are OK,…

It's my understanding that the original basis for months was the lunar cycle, which is astronomical for common definitions of the word. Part of what makes picking a calendar difficult is that the ~29.5 day lunar month doesn't fit neatly into the ~365.25 day solar year. So we've ended up with succession of adjustments and fudge factors.

There are a number of lunar calendars that have had long use. The Jewish, Islamic, and Chinese calendars, for example. They are a bit complicated for that reason. The Jewish calendar has the equivalent of "leap months", for example, while the Islamic calendar has a "year" that is ~10 days shorter than an astronomical year.

Re: Did you ever wonder why December has 31 days? (1997)

#29
To me, the most mathematically logical way to split up the calendar would have just been something like:

  01 02 03 04 05 06 07 08 09 10 11 12
  31 30 31 30 31 30 30 31 30 31 30 30 -- common year
  31 30 31 30 31 30 30 31 30 31 30 31 -- leap year
- All months 30 or 31.

- Leap month alternates between 30 and 31.

- Never have more than two consecutive months with the same day.

- Only time two consecutive months have the same number of days are Jun/Jul (30) and (Jan/Dec (31) or Nov/Dec (30)).

- Puts leap month at the end to avoid offsetting only part of the year.

- Any given 3-month span consists of either 91 or 92 days.

- Any given 6-month span consists of either 182 or 183 days, except for spans involving leap month and January, which have 184.

- First half (Jan-Jun) always consists of 183. Second half consists of 183 (leap) or 182 (common).

Re: Did you ever wonder why December has 31 days? (1997)

#30

Who is Orvitz?

Same question here. The closest i could find was Ovitz: http://en.wikipedia.org/wiki/Michael_Ovitz

Ousted from Disney by Eisner in 1997, but was given a $100 million in stock severance - Roughly around the same time this mail was written.

Post reply on HN