Why are there 12 months in a year?

[Clover Heart 979]

This is a little weird, but hear me out.

 

I was always under the impression that a year was 12 months long and that we had fluctuating numbers of days per month for mathematical reasons. There are 365.625 days in a year. I never questioned the division of months. I just always assumed that that was the system that was required in order to keep proper track of a year and the passage of time.

 

I was contemplating lunar months for a comment I was making. I had momentarily confused a standard month for a lunar one. I was talking about MLP mythos anyway (and our lack of knowledge of it) so my mistake was understandable. Anyway, irrelevant. I was curious as to how many days would be left over if we actually did go by lunar months rather than calendar months.

 

I multiplied 28 by 12 and got 336. Do you know how many days less that is from a year? 29. 

 

So I got to thinking why we needed to have 12 months in a year. Obviously my "keeping the months even with the seasons" and "accurately calculating the passage of time" ideas were debunked. However, I can see no good reason we should have 12 months instead of 13. Having 13 months makes more sense. Every month would be 28 days except the last month of the year, which would be 29 to make up for the extra day. Leap day would still be necessary in this case, in which case it could just go at the end, making the last month 30 days, or it could go at the month before the last one, making them both 29 days.

 

It just seems like 28 days makes a whole lot more sense. You even notice how in March, the days of the week all line up with the dates they did in February? That's another point that makes a lot more sense. For a whole year, our days of the week and dates would be the same as each other, meaning, for example, that every 1st of every month of that year would be a Monday, every 2nd would be a Tuesday and so on. I feel that this would be an easier way to keep track of time. There are 7 days in a week, four weeks in a month. 4*7=28, so in this regard as well, it makes more sense to have a 28-day month and 13 months in a year.

 

Does anyone know why we have this wacky 12-month system where we have to memorize that stupid poem of which months have 30 days? (Which I never get right - I just use my knuckles.) And what are your opinions on having a 13-month year as opposed to a 12-month year? I'm not saying that this will ever happen, and I think it would cause more confusion than clarity. But I think that had this been established a long time ago, it would have made a lot more sense than the system we have now.

 

Anyway, thoughts?

[Fhaolan 4,507]

You would of loved the one of the previous systems where there were 10 months (which is why some of the months are named the way they are, December literally means '10th month'.) with each month having 30 or 31 days. Yep, that only adds up to 304 days. Then you had 51 days where the year was considered 'dead' and not in any month. That's still leaving ten days and a fraction, and they gave no bucks. To deal with this there was an additional month of 21 days that appeared every other year.

[Bucky McGillyCuddy 956]

Takes the Earth 365 days to orbit the Sun.
Takes the moon 30-ish days to orbit the earth (luna cycle).

 

365 / 30 = 12-ish

 

Why they made it like that I don't know. There used to be only 10 months back in ancient Rome but they were using a solar calendar (whatever that is) and later discovered it was 60 or so days out and added in another two months to compensate. Even before that though humans have supposedly been using luna cycles as a means of dividing the year into smaller parts. We're a smart bunch when we aren't at each others throats.

[Shanks 10,817]

It is all just arbitrary anyway so whatever works I guess.

[TheMarkz0ne 962]

The Hebrew calendar is possibly the most accurate calendar we have. People speculate that our Gregorian calendar is 4 or 5 years off. The Hebrew Calendar has 13 months.  March is January and February is December.

It's confusing but leap year adds a 13 month. 

http://www.chabad.org/library/article_cdo/aid/526874/jewish/The-Jewish-Month.htm

Edited January 23, 2014 by TheMarkz0ne

[Descant 1,898]

The 12 month system stems back from Ancient Rome, where originally they more or less synced up with Lunar cycles and were from there adjusted accordingly to match with the whole "365 days to a year" thing. Heck, this is evident in the names of our months. July is named after Julius Caesar, and August after his successor Augustus.

The 24 hour day stems from Egypt, and the heavy use of the number 60 (for seconds to a minute, and minutes to an hour) was of Babylonian design. Both were picked mostly for convenience and easy divisibility.

This is all for the west, though. I'm pretty sure the Persians, the Hindu, the Punjabi, and the Khmer did it pretty much the same way.

Edited January 23, 2014 by Bard

[Galen 1,354]

The way I understand it, one year is the time in which the earth orbits the sun, and one day is the time it takes for the earth to complete one rotation. These can be observed physically by way of seasonal changes (such as temperature and roughly the amount of time the sun is up) in the case of the former and the obvious change between night and day for the latter. I suppose one month is based on how long it takes for the moon to orbit the earth, and people have observed how many times the moon orbits the earth within a year to determine how many months there are in a year. Hours and months are therefore ways to more easily measure time for us, but as EBP says, it's largely arbitrary. No single calendar will be completely accurate, but it's a good way to keep track of how much time passes beyond simple observation I guess.

[Seaweed 596]

Those wacky Romans, and that crazy character Caesar are to blame, as previously stated. Why a twelve month system? Why a system at all? I think it's just human nature to want to organize things. Makes us feel in control of something as abstract as time.

 

And really, who's Caesar to be the one to make the system? Why not Brutus? Brutus is just as smart as Caesar, Brutus is just as popular as Caesar, I think we should all just STAB CAESAR!

[Scootalove 10,692]

I think it is because of the system of which the Earth orbits around the Sun, in which it takes 365 days a year for the rotation to complete after the 12 months are up. That is the way I see it on why we have 12 months in a year.

[Galen 1,354]

I think it is because of the system of which the Earth orbits around the Sun, in which it takes 365 days a year for the rotation to complete after the 12 months are up. That is the way I see it on why we have 12 months in a year.

 

But how do we know that exactly 365 rotations of the earth occur within a year? It is easy to tell a year has gone as it is the time it takes for the earth to complete one rotation, but just how do we know precisely how many times the earth rotates within that time? This is why time is more abstract than precise. We're the only ones who really gave it a precise determinant.

[Scootalove 10,692]

But how do we know that exactly 365 rotations of the earth occur within a year? It is easy to tell a year has gone as it is the time it takes for the earth to complete one rotation, but just how do we know precisely how many times the earth rotates within that time? This is why time is more abstract than precise. We're the only ones who really gave it a precise determinant.

If you ask me, I think the Earth rotates only once within a year. We might not know for sure, but it is better to take some guesses and speculations on whether it could be true.

[Judgement 445]

Maybe it's because people think 13 is an unlucky number? I mean, why do hotels not have 13 floors? People are scared to death of that number.

Edited January 23, 2014 by Judgement

[SasQ 1,382]

 

 

So I got to thinking why we needed to have 12 months in a year. Obviously my "keeping the months even with the seasons" and "accurately calculating the passage of time" ideas were debunked. However, I can see no good reason we should have 12 months instead of 13. Having 13 months makes more sense.

 

Interesting question! I love when people start questioning their knowledge and start thinking on their own. Unfortunately they are rare exceptions. So good for you that you're in that group.

 

It is often said that a year has 365 days, because after 365 full rotations of the Earth around its own axis (seen as 365 rounds of the Sun around the Earth from our perspective) we can see exactly the same configuration of stars in the night sky. That is, the Earth has done a full cycle around its orbit around the Sun. (That's how we know it, @). And that there are around 12 lunar cycles (moons, or months) in that period.

 

But I have always thought that something fishy is going on here. And now you noticed that too.

 

First off, as you correctly noticed, lunar months are around 28..29 days long. But our calendar months have 30..31 days (with one exception of February, which has only 28..29). This is 1..2 days off each month, which taken 12 times (the number of months) will amount for around another month. So what the hell is going on here?

 

There's something which can possibly get us closer to the answer: the Zodiac. Ancient Babylonians observed that all "wandering stars" (or "planetes" in Greek) travel along nearly the same path in the night sky as the Sun travels through the day. This path is called "ecliptic", and it is actually the plane of our Solar System, as seen from Earth, because all planets and the Sun lie in this same plane.

 

So they took ecliptic and divided it into 12 equal parts. Then they took the constellations which are seen in the background of the ecliptic and named them. These are the 12 signs/houses of the Zodiac: Aries (ram), Taurus (bull), Gemini (twins), Cancer, Leo, Virgo (maid), Libra (balance scale), Scorpio, Sagittarius (half-horse, half-man, with a bow), Capricorn (half-goat, half-fish), Aquarius (the man with a mug of water), Pisces (fishes). Babylonians used 360-degree angle measure for the full circle, so when divided into 12 equal parts this gives us 30 degrees angle for each Zodiac house.

 

 

This seems much closer to our calendar system, isn't it? ;> 12 Zodiac houses = 12 months, around 30 days each (30 degrees angle), which pretty much coincides with the lunar month. And 360 as the number of degrees in the full circle is pretty close to 365 days. But why did they missed out those 5 days? They were good astronomers after all, right?

 

Well, 360 has more divisors than any other number before it. Such numbers are called "highly composite" or "versatile". 360 can be prime-factored into 2*2*2*3*3*5, and different combinations of those factors give us a lot of useful divisors: 360 can be divided by 1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 18, 20, 24, 30, 36, 40, 45, 60, 72, 90, 120, 180, 360. Pretty much, eh? But 365 has only two prime factors: 5*73, so it is divisible only by 1, 5 ,73, 365. Kinda sucks Also, it is quite easy to divide a circle into 12 equal parts. Just construct a hexagon like this:

 

and then connect the points where the circles intersect each other to bisect the sides of the hexagon and find the other 6 points, which amounts to 12 equal parts around the circumference.

 

This could explain why did they choose the number 12 as the number of months. First they divided the ecliptic into four equal parts by making a "cross" from perpendicular lines. This would be the 4 seasons. These four key points on the ecliptic match the four key points on the Earth's orbit around the Sun: two equinoxes (where day and night have the same length) and two solstices (where day is longer, as in summer solstice, or the night is longer, as in the winter solstice). Then they subdivided them further into 3 equal parts each. This gives 12 months. 12 is again a versatile number. It has the following divisors: 1, 2, 3, 4, 6, 12, which is more than any number before it. The same goes with 24 (which is the number of hours in the solar day) and 60 (which is used as the number of minutes in an hour). Versatile numbers are best choice for the systems of units of measures and weighing, because they have many divisors (they can form many different patterns).

 

There's one more evidence that Zodiac has something to do with it: Every month has one house of Zodiac ascribed to it. That's because when you look at where the Sun rises from the horizon in that month, you will see some constellation of the Zodiac behind it in the background. Each month there will be a different constellation of the Zodiac there.

 

You can notice that at the day of vernal equinox (the day in Spring when day and night are equal) the Sun rises at the boundary of Aquarius at present:

 

 

That's the whole story behind this "Age of Aquarius" thingy said by the New Age movement representatives: the Ancients used Zodiac signs to measure the ages, too. They looked at which sing of the Zodiac the Sun rises at the vernal equinox. This is one of the "corners of the world", where "world" means the "age" or "era". Each every 2160 years the axis of the Earth rotates a bit, which causes the whole Zodiac shift one house back, and we see a different sign of the Zodiac constellation behind the Sun this particular day. This phenomenon is called "precession of the equinoxes". The whole cycle takes around 25920 years (so called Platonic Year), which is 12 x 2160. (See? 12 again!) The previous age was the age of Pisces. It started nearly when Jesus has born. That's why they used a fish as his logo Previously there was the age of Aries (ram), and recall all the Hebrew myths about the Lamb of the Lord which will come. Before that, there was the age of Taurus (bull), and recall what animal has been worshiped in Ancient Egypt at that time And the golden bull still worshiped by the Israelites when Moses came down from the Horeb mountain to announce the new age of Aries -- no wonder he was mad that they still worship the symbol of the age which already passed over Unfortunately, modern astrologers know nothing about the precession, so they still ascribe Aries to March, despite the Sun rising in Aquarius in that month. They're off by around 4000 years then, since the Sun has been rising in Aries in March around 4000 years ago  -_-

 

 

 

It is all just arbitrary anyway so whatever works I guess.

 

 

In the case of ancient measurement systems nothing is "arbitrary". Don't underestimate it just because you don't understand it.

 

Take a piece of string 1 meter long, and attach some weight at its end. Then swing it, and measure the time of one swing. It will be equal to one second. Coincidence? 

[Castle Bleck 19,634]

Because 13 would give us bad luck all year long.

Edited March 2, 2014 by Anti-Villain

[Doctor XFizzle 8,672]

Thank god for egotistical Roman emperors otherwise my birthday would be in October.

[Something Floaty 1,334]

To make room for holidays, of course. Can you imagine trying to cram all of them into only 10 months?!

[IcyHaze 595]

I read up on all of this on an science essay written by the late Isaac Asimov - one of the greatest scientific authors of all time.

 

tl:dr version:

 

Certain ideas were in place, but they were found to be inaccurate - so scientists began to sort out the kinks.

Everything worked well, and the Pope kept Easter on the Lunar calendar, hence why it changes all the fucking time.

It was fine until a scientist realised that they were still inaccurate by a tiny amount - so the pope made the world change their calendars back a few months/years/whatever to fix it, and introduced leap years to fix it.

 

Side note:

  Aman sorted out the whole "AD and BC" system...

BUT GOT IT WRONG as things were worked out again - 6 years incorrect in fact.

 

Hence, Jesus is listed as being born in 6 B.C.

 

Weird, huh?

[DubWolf 20,687]

Just an observation a teacher showed me (or I guess, a fact):

 

Sept-ember

Oct-ober

Nov-ember

Dec-ember

 

I believe we had 10 months in the past, though we never had a Hexember or Unember I believe  .

Honestly, I don't really know why we have 12 months! We obviously need 7 days in a week for religious purposes (boy, I'm glad people don't argue about that :okiedokielokie: !!), so it would make some sense to have 13 months with 29 days. But, a lot of people have disfavored the number 13, even removing that number from building floors and airline logos.

[SasQ 1,382]

Sept-ember

Oct-ober

Nov-ember

Dec-ember

I believe we had 10 months in the past

 

Not quite. This is because the year was once starting in March (the month of Mars), with the vernal equinox (when the day & night are of equal length in Spring). This was the real beginning of the calendar. Then, counting from March, you have September as seventh month, October as eighth, November as ninth, and December as tenth. But then there was January (named after Roman god Janus), and February, as the two last months in a year. The year ended with the end of the winter. 

 

There's an interesting trace of this fact in a letter from a mathematician Niccolo 'Tartaglia' Fontana to another mathematician Gerolamo Cardano, where Tartaglia describes his method of solving cubic equations in a form of a poem (in Italian). The last four lines of this poem are (in English):

 

    I found these, & not with slow steps,

    In thousand five hundred, four and thirty

    With very firm and strong foundations

    In the city girded around by the sea.

 

Tartaglia lived in the Republic of Venice where, until its end in 1797, the year did not begin on January 1 as today, but officially on March 1. Therefore, February 12 and 13 of our year 1535 were still in the Venetian year 1534.

 

Because 13 would give us all bad luck all year long.

 

13 is know as the unlucky number only from 1307, because in October 13th, 1307, on Friday, hundreds of the Knights Templar were arrested in France, charged of heresy & worshiping the devil, and prosecuted to death by the Church on behalf with the State. It was surely unlucky day for them at the very least  The Julian calendar, however, has been used long before that date, with 12 months, when no one considered 13 "unlucky" yet.

 

What's more, 13 as unlucky number is particular to the Western tradition. It isn't that much unlucky in Eastern tradition. They, on the other hand, consider the number 4 as unlucky, because in Japanese the number 4 is "shi", which also means "death". I heard that they are afraid of that number to the point that in many hotels there are no 4th floor or 4th room.

 

P.S.: You might be interested in this thread, too

Edited March 2, 2014 by SasQ

[NomDeSpite 452]

Because seven ate nine. I've heard this joke before.

Edited March 2, 2014 by NomDeSpite

[Zyla Fae 5,411]

For the same reason that the US uses their own stupid measuring systems, and the common numbering system is Decimal instead of Dozenal, and a bunch of other stupid stuff like that

 

Because it for a stupid reason a long time ago that's how someone decided it should be, and people don't want things to change (Even when the changed version makes so much more sense) 

[Sekhayet 253]

 

This is a little weird, but hear me out.

 

I was always under the impression that a year was 12 months long and that we had fluctuating numbers of days per month for mathematical reasons. There are 365.625 days in a year. I never questioned the division of months. I just always assumed that that was the system that was required in order to keep proper track of a year and the passage of time.

 

I was contemplating lunar months for a comment I was making. I had momentarily confused a standard month for a lunar one. I was talking about MLP mythos anyway (and our lack of knowledge of it) so my mistake was understandable. Anyway, irrelevant. I was curious as to how many days would be left over if we actually did go by lunar months rather than calendar months.

 

I multiplied 28 by 12 and got 336. Do you know how many days less that is from a year? 29. 

 

So I got to thinking why we needed to have 12 months in a year. Obviously my "keeping the months even with the seasons" and "accurately calculating the passage of time" ideas were debunked. However, I can see no good reason we should have 12 months instead of 13. Having 13 months makes more sense. Every month would be 28 days except the last month of the year, which would be 29 to make up for the extra day. Leap day would still be necessary in this case, in which case it could just go at the end, making the last month 30 days, or it could go at the month before the last one, making them both 29 days.

 

It just seems like 28 days makes a whole lot more sense. You even notice how in March, the days of the week all line up with the dates they did in February? That's another point that makes a lot more sense. For a whole year, our days of the week and dates would be the same as each other, meaning, for example, that every 1st of every month of that year would be a Monday, every 2nd would be a Tuesday and so on. I feel that this would be an easier way to keep track of time. There are 7 days in a week, four weeks in a month. 4*7=28, so in this regard as well, it makes more sense to have a 28-day month and 13 months in a year.

 

Does anyone know why we have this wacky 12-month system where we have to memorize that stupid poem of which months have 30 days? (Which I never get right - I just use my knuckles.) And what are your opinions on having a 13-month year as opposed to a 12-month year? I'm not saying that this will ever happen, and I think it would cause more confusion than clarity. But I think that had this been established a long time ago, it would have made a lot more sense than the system we have now.

 

Anyway, thoughts?

 

 

This has already been developed. It's called the Tranquility Calendar.

[Khaoios 1,970]

Why do we have 12 months in a year is a very good question, tbh.   As a history major as well, we got our Calender from the ancient Aztecs, Mayans, and the Incas and it has been widely used since.  Why we use it, I am not sure.  Remember though, that such a question like this dates back to before Christ, Himself, walked the earth. Your talking about to earliest human civilizations, or somewhat later, like the early Mesopotamian, Egyptian, Persian, Roman, Greek, and Hebrew. That's as far as I know, but i think some deeper research will help you. 

Edited March 5, 2014 by Promethean Alicorn