You are Here: Home >< Physics

# Days of the months ... watch

1. Hi,

why do some months only have 30 days and some 31 days, and why does only february has the least days - 29 days?

Thanks.
2. 28.
29 on leap years only.
3. it's based around greek or roman [i think] myths, and how long hercules [i think] took to do a set of tasks givwen to him by some other God.
There were 10 tasks in total, but two more popped up at the end, [january and february] hence why OCTober is the 10th month, NOVember is the 11th, and DECember is the 12th.

Um, I think that's right.
4. oh, and Feb has 28 or 29 because each year is 365.25 days long, so they make up for it every 4 years.
5. (Original post by maxfire)
it's based around greek or roman [i think] myths, and how long hercules [i think] took to do a set of tasks givwen to him by some other God.
There were 10 tasks in total, but two more popped up at the end, [january and february] hence why OCTober is the 10th month, NOVember is the 11th, and DECember is the 12th.

Um, I think that's right.
I've always wondered why, seeing as they were supposed to be so smart, the Romans didn't add those two months at the end of the year..then spetember, october, november and december would be in the right places
6. (Original post by *Hannah)
I've always wondered why, seeing as they were supposed to be so smart, the Romans didn't add those two months at the end of the year..then spetember, october, november and december would be in the right places
Who knows why they did it. I'm assuming it was some Roman nut thinking it would be funny.
Anything could have happened, it was over 2000 years ago.
7. (Original post by maxfire)
Who knows why they did it. I'm assuming it was some Roman nut thinking it would be funny.
Anything could have happened, it was over 2000 years ago.
Does it not also depend on the moon? I mean full moon after a month...
My question was rather why does the time change for a full moon? Does it have to do with the speed of the moon? or the radius of the earth?cus its ellipse..
8. (Original post by Ben77mc)
28.
29 on leap years only.
Yes that's right.
9. (Original post by lnx)
Does it not also depend on the moon? I mean full moon after a month...
My question was rather why does the time change for a full moon? Does it have to do with the speed of the moon? or the radius of the earth?cus its ellipse..
The earth tilts towards and away from the sun, hence the seasons. So I'm guessing we see the moon from different angles all the time.
A lunar month is not the same as a calendar month.
10. Hmm. How that fit into a Physics Forum?
Numbers of days in a month is not a physical constant. Hell its not even constant. The lunar cycle is getting longer. Which has nothing to do with months now....
BAHHH
11. (Original post by Mehh)
Hmm. How that fit into a Physics Forum?
Numbers of days in a month is not a physical constant. Hell its not even constant. The lunar cycle is getting longer. Which has nothing to do with months now....
BAHHH
Sp physics is not concerned about the motion of moons? earth?
12. Well the number of days in a month is completely arbitrary. It just depends on whatever calendar system you choose to use. It has nothing to do with physics really.
13. (Original post by lnx)
Sp physics is not concerned about the motion of moons? earth?
I do believe the OP was refering to a Gregorian calender, which is based off of a revolution of the sun around of the earth. Now as numbers go, that would be called arbitary, as we are just as likely to have evolved on a planet with a 400 day long year.
Further more, the Gregorian tries to divide a period with another period which results in a non integer (a real number). This means that if we want to further sub divide the year into months (which in meant to be a lunar cycle, but really isn't (a month is far too long)) then we would end up with weird number of days per month no matter how you cut it. By trying to jammy the concept of a lunar cycle in there they just really F%&£ed it up royally by introducing 3 arbitary constants that happen to be measurable, which basically means you end up with lots of real numbers floating about.
The result is some guy* had to sit down somewhere to try and reconcile all the numbers to avoid calender drift (the seasons drifting from the calender, which lunar calendars get).
The result is that we have 365 and a bit days to a year with 30 day long months in some cases, and others with 31 except feb which we just can about give up on owing to the fact that there are about 5 rules to how many days that month has and they damned well all conflict.

So short answer to the OP is that Pope Gregory XIII said "what that guy said" to Dr Aloysius Lilius. Thus forever more we have the most complicated calender you could possibly imagine.

*This came as a palpal decree, that we shall have a calender that didn't have all this gawd awfulness that came with seasonal drift, but we damned well keep the usage of terms like DAYS, MONTHS and YEARS.
14. (Original post by Mehh)
I do believe the OP was refering to a Gregorian calender, which is based off of a revolution of the sun around of the earth. Now as numbers go, that would be called arbitary, as we are just as likely to have evolved on a planet with a 400 day long year.
Further more, the Gregorian tries to divide a period with another period which results in a non integer (a real number). This means that if we want to further sub divide the year into months (which in meant to be a lunar cycle, but really isn't (a month is far too long)) then we would end up with weird number of days per month no matter how you cut it. By trying to jammy the concept of a lunar cycle in there they just really F%&£ed it up royally by introducing 3 arbitary constants that happen to be measurable, which basically means you end up with lots of real numbers floating about.
The result is some guy* had to sit down somewhere to try and reconcile all the numbers to avoid calender drift (the seasons drifting from the calender, which lunar calendars get).
The result is that we have 365 and a bit days to a year with 30 day long months in some cases, and others with 31 except feb which we just can about give up on owing to the fact that there are about 5 rules to how many days that month has and they damned well all conflict.

So short answer to the OP is that Pope Gregory XIII said "what that guy said" to Dr Aloysius Lilius. Thus forever more we have the most complicated calender you could possibly imagine.

*This came as a palpal decree, that we shall have a calender that didn't have all this gawd awfulness that came with seasonal drift, but we damned well keep the usage of terms like DAYS, MONTHS and YEARS.
What I meant was, we get full moon after each month right? But why is it sometimes 30 days and sometimes 31 days? Do you know what I am trying to say?
15. (Original post by lnx)
What I meant was, we get full moon after each month right? But why is it sometimes 30 days and sometimes 31 days? Do you know what I am trying to say?
No.

No.

Yes, but you're an idiot.
16. (Original post by lnx)
What I meant was, we get full moon after each month right? But why is it sometimes 30 days and sometimes 31 days? Do you know what I am trying to say?
The lunar cycle doesn't follow calendar months - full moons don't occur on the same day each month. Have a look at

http://www.woodlands-junior.kent.sch.uk/time/moon/

Next question - shouldn't full moons always fall on Mondays?
17. (Original post by TableChair)
No.

No.

Yes, but you're an idiot.
Screw you.
18. (Original post by lnx)
Screw you.
lol

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: August 6, 2009
Today on TSR

### He lied about his age

Thought he was 19... really he's 14

### University open days

Wed, 25 Jul '18
2. University of Buckingham
Wed, 25 Jul '18
3. Bournemouth University