
Did you ever wonder why December has 31 days? (1997) - soegaard
http://projects.csail.mit.edu/gsb/old-archive/gsb-archive/gsb1997-02-14.html
======
cedsav
And it's wrong. The email is from 1997, but now you can look it up on
wikipedia:
[http://en.wikipedia.org/wiki/Julian_calendar](http://en.wikipedia.org/wiki/Julian_calendar)

Short version - Julius didn't name the month after himself, the roman Senate
did. There's good indications that July and August had 31 days before the
reform, and February has less days because it was the last month of the year.

~~~
frogpelt
I have thought February would make more sense as the last month of the year.
But I guess that's because I live in the Northern Hemisphere and having the
year start right after Winter starts seems like a bad combination.

EDIT: Apparently, 90% of the world's population lives in the Northern
Hemisphere. Source: [http://bigthink.com/strange-maps/563-pop-by-lat-and-pop-
by-l...](http://bigthink.com/strange-maps/563-pop-by-lat-and-pop-by-long)

~~~
shawabawa3
You can also kind of tell March used to be the first month by how september-
december are named (7 8 9 10)

------
sltkr
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 to a senatus consultum quoted by Macrobius,
> Sextilis was renamed to honor Augustus because several of the most
> significant events in his rise to power, culminating in the fall of
> Alexandria, fell in that month.

The fact that February has the fewest days makes sense considering it was the
last month of the Julian year (March was the first, hence July and August were
called quintilis and sextilis, for fifth and sixth, respectively). It doesn't
quite explain why the 31-day months are distributed unevenly over the year,
but if you are going to take days off, it makes sense to take them off the
last month of the year.

1\.
[https://en.wikipedia.org/wiki/Julian_calendar](https://en.wikipedia.org/wiki/Julian_calendar)
2\.
[https://en.wikipedia.org/wiki/Augustus#Month_of_August](https://en.wikipedia.org/wiki/Augustus#Month_of_August)

~~~
hobbes300
Contradicting Wikipedia does not equal a lack of truth.

~~~
sltkr
No, but information on Wikipedia tends to be accurate and based on reliable
sources -- when a person contradicts Wikipedia and fails to provide any
sources of their own, they are _usually_ wrong. Not necessarily, of course,
but often enough to say the burden of proof lies with the person making the
unsubstantiated claim.

~~~
saraid216
Uh. There was a source provided: 1911 Encyclopedia Britannica.

I wouldn't call that more reliable, but it's still as valid a source as
Wikipedia.

~~~
mgraczyk
The 1911 Britannica is not the source provided. The source is a hypothetical
entry in an encyclopedia that most people don't have. That is not as valuable
a source as Wikipedia because I cannot easily verify that the 1911 Britannica
corroborates the facts in this email.

~~~
acqq
The text of the whole 1911 Britannica is just one Google away:

[https://archive.org/details/EncyclopaediaBritannica1911HQDJV...](https://archive.org/details/EncyclopaediaBritannica1911HQDJVU)

[http://en.wikisource.org/wiki/1911_Encyclopædia_Britannica](http://en.wikisource.org/wiki/1911_Encyclopædia_Britannica)

------
jader201
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).

~~~
Anon84
Even easier. 13 months of 28 days with one or two "leap day" per year make up
365-366.

~~~
shortsightedsid
Which is like to a Lunar Calendar with 1 or 2 holidays at the end. So, you
have 13 months, each month is 28 days. At the end of the year you get 1 or 2
days off free!

------
Aardwolf
"Did you ever wonder why December has 31 days?"

Honestly? No.

I did wonder why each of the 12 months got their specific amount of days,
sure. I even wondered it about the special one, February, individually. But
wondered it about December individually? No.

------
peapicker
I vote for 30 days for all months, followed by a 5 or 6 day festival
(depending) at the end of the year. ;)

~~~
gabriel34
I approve of this with one change: the festival would last to the second
exactly as long as it would take to synchronize the calendar to our orbit
around the sun (no leap years or anything).

Could you imagine a little more than five days with no representation on the
calendar? Truly a "let everything go" period of time. Society would fall into
chaos, no appointments could be made for those days because there is no way to
address an exact point in time before the calendar reestablishment; truly an
environment for a giant worldwide party.

In reality tough we would just call it the 13th month, or the minimonth and
everything would go business as usual :/

------
mcv
I thought it was because of the knuckles.

But if you want to discuss Romans and calendars, you've got to mention that
Mars was there first month (because it's such a great month to start a fresh
military campaign). So February was the last, and got whatever remains.

Why July and August both have 31 days, I have no idea. Augustus' jealousy
sounds plausible, but apparently it's not true. So what's the real reason for
this?

------
gnuvince
Because it falls on my middle finger's knuckle.

~~~
gabriel34
ring finger in the version of the mnemonic algorithm I know

------
Thiz
I like the universal calendar with 13 months, all with 28 days in four weeks.

One extra day at the end of the year. Another extra day for leap year.

~~~
gabriel34
How about no months, 52 weeks per year with a 53rd 5-day week on leap years
which would also correct leap seconds and such.

I have always organized myself weekly, so does everyone around me. I think
it's much more natural than months, specially because you have week-ends which
mark the end of each week, but not a month-end, you just drift from one month
to the other, nothing happened (except bills and paychecks and whatnot, which
can also be made weekly)

~~~
Thiz
Then why not extend the week to a ten day period?

The decimal system seems to work better.

~~~
gabriel34
Because then we would have to alter the moon's orbit :D

Interestingly, contrary to the seasons, the moon's phases bears no effect on
our lives since the artificial illumination of the cities. The seven-day week
could be a ten day week; on the other hand I would be weary of ten-day week
because of possible connections with my (and humans in general) metabolism and
internal clock. Perhaps five days worked per two days rested is our optimal.
There is no reason why ten would be the magical number, but seven seems to be
working; further studies are necessary.

------
bladedtoys
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](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.

------
leh
According to wikipedia, the julian calendar already had 31 days for august so
the explanation of the article doesn't seem to be correct.

[https://en.wikipedia.org/wiki/Julian_calendar](https://en.wikipedia.org/wiki/Julian_calendar)

------
adders
This is a un-true myth according to Wikipedia
[https://en.wikipedia.org/wiki/Julian_calendar#Sacrobosco.27s...](https://en.wikipedia.org/wiki/Julian_calendar#Sacrobosco.27s_theory_on_month_lengths)

------
ds9
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, apparently, for years and days,
yet weeks and calendar months are arbitrarily imposed.

~~~
ghkbrew
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.

~~~
Thrymr
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.

------
dang
Based on the comments in this thread, it seems the post is cute but wrong, so
I'm burying it.

------
jauco
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.

~~~
sdague
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.

~~~
zowch
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.

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

~~~
sirn
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.

~~~
gabriel34
Interesting. What about February and leap years?

Does khom and yon have meanings?

The rest of the month's name is based on what?

~~~
sirn
February is using a special suffix, "-phan".

Both "-khom" and "-yon" means "come" or "arrival". Since our month names are
basically a Zodiac in Hindu astrology, "Mokkarakhom" could be translated to
"the arrival of Capricorn" (Mokkara/Makara) or April "Mesayon" is "the arrival
of Aries" (Mesa).

------
soegaard
GSB Explained: [http://projects.csail.mit.edu/gsb/archives/gsb-
msg00080.html](http://projects.csail.mit.edu/gsb/archives/gsb-msg00080.html)

------
bttf
Anyone else share a craving for Girl Scout cookies after reading this?

------
dasil003
Who is Orvitz?

~~~
RaSoJo
Same question here. The closest i could find was Ovitz:
[http://en.wikipedia.org/wiki/Michael_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.

------
batmansbelt
No.

------
finalight
er...don't make sense

------
crystaln
If it were true, that would mean Augustus messed up our calendar in addition
to his biggest sin - sending us into the dark ages by making Christianity a
viable religion. We are still in the shadows.

~~~
crystaln
Why was this down voted?

