# Basic calendar questions

1. Jul 16, 2013

### Phy_enthusiast

As earth takes 365 days to revolve around sun then why are days grouped into 12 months and we dont have calender that goes from1 to 365.

2. Jul 16, 2013

### phinds

We DO have a calendar that goes from 1 to 365. It is called the Julian calendar. You can use it if you like. Good luck with that.

3. Jul 16, 2013

### Phy_enthusiast

ok. than why are they grouped int0 12 months carrying 30 or 31 days?????

4. Jul 16, 2013

### Bandersnatch

Days are grouped into 12 months because the Romans liked it that way. There is no other reason but historical circumstances.
It's the same kind of question as asking why is the day divided into 24 hours. There's simply no physical meaning behind it.

And just to clarify phinds' comment, it was a jab at your saying the year is 365 days long, which is how it was assumed to be before the Gregorian reform. The actual length of a year is not a well-rounded integer number of days, but is closer to 365.25. That's not the exact value either, but it is what the Gregorian calendar uses as the calculation basis, causing every fourth year to have 366 days, and producing less of an accumulating error.

5. Jul 16, 2013

### Gerinski

Is it not partly related to trying also to have some reference to the lunar cycle?

6. Jul 16, 2013

### Phy_enthusiast

I think it is not partly but fully related to lunar cycle....

7. Jul 16, 2013

### Bandersnatch

Yes, you're right. It's true as far as the early roman calenar goes(the one with ten months in a year and a gap during winter).

However, from that base lunar calendar, a number of alterations were made that eventually ended up being the calendar that we know. These alterations, before the Julian reform, were based mostly on the Roman perception of lucky and unlucky numbers and altering the length of months to fit in a year.

If the months were fully informed by lunar phases, we'd have 12.3 months in a year, each with 29 or 30 days in it.

8. Jul 16, 2013

### Gerinski

At any rate the question is relevant: with our current much more precise knowledge of the solar system's dynamics, couldn't we conceive of a more rational timing & calendar system? one which is much more regular (and hopefully decimal-based), not having hours of 60 minutes, days of 24 hours, months of different lengths, leap-years and all that b*t?
Have any proposals been made for a more rational timekeeping method?

9. Jul 16, 2013

### phinds

Why? What would be the point? You seem to be trying to solve a problem that doesn't exist. Really, don't you think there are more important things to worry about?

10. Jul 16, 2013

### SteamKing

Staff Emeritus
11. Jul 16, 2013

### Integral

Staff Emeritus
In the US we cannot even convince people to use the metric system, you want to change the calendar! It can never happen. Just to much inertia and tradition and no real reason.

12. Jul 16, 2013

### SteamKing

Staff Emeritus
Those ten day weeks are a killer. Today, the French can barely struggle thru four and a half days a week. And what's the deal with no weekend?

I wish they had bagged the metric system with the weird calendar, just so we wouldn't have to hear about how great it is all the time.

13. Jul 16, 2013

### SW VandeCarr

A more rational revision of the current Roman based calender has been proposed but it hasn't caught on either. It divides the year into four quarters of 91 days each with three months of 31,30 and 30 days (364.days). The remaining day is called World Day comes between a Saturday and Sunday. 364 is divisible by 7, so every date falls on the same day of the week every year. Leap years are handled the same way and the World Calender follows the Gregorian Reform for leap years. Every common year has the same calendar.

http://en.wikipedia.org/wiki/The_World_Calendar

Last edited: Jul 16, 2013
14. Jul 16, 2013

### SW VandeCarr

Astronomers often use Julian dates which are based only on days. Today's Julian date is 2,456,489.5 (16 July, 2013). The days are counted from 1 January, 4713 BCE.

http://aa.usno.navy.mil/data/docs/JulianDate.php

Last edited: Jul 16, 2013
15. Jul 16, 2013

### Bobbywhy

Meters and kilograms are not just a craze
That the world is metric doesn’t seem to faze
The US and England who remain in a daze
Confined to their islands immersed in a haze
At two ostriches the world continues to gaze

Bobbywhy

16. Jul 17, 2013

### Phy_enthusiast

The time keeping method by lunar cycle is the gift of ancient civilisation (mainly indians), modern civilisation should infact find out new method based on modern physics and astronomy.

17. Jul 17, 2013

### Gerinski

I guess we are forced to keep using the day-night cycle anyway, otherwise we would mess up with our circadian rhythm, and it is possible that the lunar cycle has biological implications too.

18. Jul 17, 2013

### phinds

Why? What would be the point? You seem to be trying to solve a problem that doesn't exist. Really, don't you think there are more important things to worry about?

19. Jul 17, 2013

### AlephZero

Not true so far as "England" is concerned (I assume you actually mean the UK).

Apart from a couple of things (pints of beer, and road distances and speed limits in miles) the UK has been using metric for decades.

But if course we still have to waste our time over engineering mixups with the US working in BTUs, kips, degrees F, etc, etc ....

20. Jul 17, 2013

### Gerinski

I believe you're still measuring the surface of a building in square feet, fuel consumption in miles per imperial gallon, and yards are still pretty much in use.