Why are there 365 days in a year?
Ok… here’s my theory and it doesn’t add up.
7 days in a week
4 weeks a month
52 weeks in a year
52 x 7 = 364
What happened to the other day???
Please, don’t write back saying “daylight savings time”. Up and down only 1 hour - nothing gained nor lost there. Maybe Moon axel’s or the Egyptians played some kinda joke on us… If someone can answer this 1 question for me, I’ll send you a photo of my dog naked.
Chrystie
Just a tiny nitpick…and not because this is the wrong forum…even though it is…
A year is 365.25 days long. Hence a leap year every 4 years.
Just a further nitpick - there are 365.2422 days in a year.
In the time it takes the Earth to make one complete orbit around the Sun (1 year) the Earth spins about its axis about 365 times. A week (7 days) is an arbitrary measure.
Haj
don’t ask…
Would you believe…a weak battery in my calculator?
God I love simuposts…
I’m sorry and thanks for the advise. I’m a newbie 
Chrystie
Oh, and we should realise we are being very insular here in that calendars other than Christian have a different “year”.
Look here
OK, I’ll take a shot.
It takes 365.2422 and change days for the earth to go around the sun. We have standardized a year as that long so that the months don’t shift relative to the seasons. IIRC some time in the Middle Ages Pope Gregory basically called for a month to be omitted because Easter was shifting itself into summer. Something like that.
You may remember that 2000 was a leap year, but 1900 was not. If we had a leap year every 4 years, every year would average 365.25 days. To correct for the difference between the actual 365.2422 and 365.25, you miss a total of 9 leap years over 1000 years.
So, off the top of the head, there are 250 - 9 leap years per 1000 years = 241 leap years/1000 years. So, 365,000 days in 1000 years + 241 extra leap days = 365,241 days/1000 = 365.241 days per year. The extra 0.0012 between 365.2422 and 365.241 is made up in leap seconds every now and again, I presume. 0.0012 days = 1.7 minutes, so I suppose we are pretty close.
Or maybe I meant here
Lemme just add that others use different years. The Jews use a hybrid lunar/solar calendar with a great system of leap years and months which I was taught repeatedly in Sunday school and promptly forgot. All I remember is something about Adar Aleph and Adar Bet, but I don’t remember how often they add the extra leap month.
Muslims and the Chinese use a strict lunar calendar, based on the moon’s 4 week cycle. This is why Chinese New Year and Ramadan shift in the seasons. Or something like that. I’m a biologist, I really shouldn’t be answering these.
Well, nice meeting you too Mr. Vocabu-fary! Maybe that missing day was your birthday!
[Moderator Hat ON]
Moving thread to General Questions.
[Moderator Hat OFF]
don’t ask wrote:
Just an even further nitpick:
There are 365.2422 MEAN SOLAR days in a mean tropical year.
The Mean Solar Day is the average amount of time it takes the Earth to go around so that the sun appears in the same position in the sky. By definition, a mean solar day is exactly 24 hourse long.
The amount of time it takes the Earth to go around so that an arbitrary star (such as Sirius, Canopus, Regulus, etc.) appears in the same position in the sky is called the mean sidereal day. One mean sidereal day works out to approximately 23 hours, 56 minutes, and 4 seconds. One mean tropical year is 366.2417 sidereal days long.
And note that I’ve emphasized this to be the length of the mean tropical year. The tropical year is the amount of time from one vernal equinox to the next. This value is not quite the same from year to year, due to various wobbles in the precession of the equinoxes, so the mean (average) value is usually used. There are other definitions of the year, such as the anomalistic year, which is the amount of time it takes the Earth to go all the way around its elliptical orbit once, i.e. from one perihelion (or one aphelion) to the next. Unlike the tropical year, all anomalistic years are exactly the same length, so there is no need to compute a “mean” anomalistic year.
Don’t get me started on the length of the “day” on other planets…
edwino wrote:
It was Pope Gregory XIII, and it was in 1582, which would be the Renaissance, not the Middle Ages. And the switch-over from the Julian calendar to the Gregorian calendar only required the omission of 10 days, at that time. (Countries that switched over to the Gregorian calendar in later years, e.g. the newly-formed Soviet Union in 1917, had to omit more than 10 days.)
We now return to your regularly-scheduled General Question, already in progress.
Haj is completely right.
And if he didn’t get you completely past your stumbling block…
If you are wondering why someone didn’t pick a number of days for a year that is conveniently divisible by seven, the answer is that no one picked the length of a year. Its length is determined by the earth orbit around the sun. People just measured it.
Dang… About 20 posts came up while I was posting. I feel pretty unneeded now.
Which allowed Cervantes and Shakespeare to die on the same date 10 days apart and for Washington to be born on February 11, 1731 but recorded in history books as born on, February 22, 1732.
To be even more precise regarding dates, people who went to bed on October 4th, 1582, woke up on October 15. Sort of a small scale Rip van Winkle effect.
Which explains why old dates are comminly written with OS next to them. It means old style and is used to differentiate Gregorian from Julian dates.
I always had heard the switchover was in September.
ghoul:eddie {103} cal 9 1752
September 1752
Su Mo Tu We Th Fr Sa
1 2 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
If I recall correctly, there were riots because of people protesting paying a full month’s rent for less than three weeks’ pay.