calendar months

[laurenhogan]

Why do we have calendar months with a different number of days

[Clanad]

Primarily to keep the months aligned with the lunar cycle as much as possible. Since even that produces an error an extra day is added each four years, hence the "leap year".

[bernardo]

Because 365 is not divisible by 12.

[Quizmonster]

In the original Roman calendar, the year began in March, so December (from Latin �decem' = 10) was the tenth month. Before Julius Caesar, March, May, July and October had 31 days. (Of course, �July' at that time was called Quintilis - the fifth month - it became �July' only later, to honour Julius Caesar.) All the rest had 29 days, except February which was the last month. This comes to a total of 355 days, so every two years an extra 22 or 23 days had to be added.This was done by inserting a new month called Intercalis, starting from February 24th and lasting 27 or 28 days. Over a 4-year period, then, a series of 355, 378, 355 and 377-day years existed. The 4 days too many that this system created were simply adjusted �out of sight' from time to time! Julius Caesar devised a system in which 365 days would replace 355 and an extra leap-day would straighten things up every fourth year. The ten additional days were shared out among the existing months, so January, March, May, July, October and December had 31 and the rest had 30, with February on 29 normally and 30 in leap years. Sextilis - the sixth month - was later renamed in honour of Augustus. Clearly, he could not be granted a shorter month than Julius Caesar, so a day was �stolen' from February to bolster his month! And which day was taken? Well, the very last day of the year...namely February 29th or 30th. Thus, it now has only 28 or 29 days.

[New Forester]

When the Julian calendar first began, apparently they made an error. The requirement to have one leap year after every three "normal" years was misinterpreted by the clerks, and for the first few cycles they had a leap year every three years instead. Then they had to skip a leap year to un-catch-up... They also did not realise that the year is slightly less than 365-and-a-quarter solar days, and so you have to skip the leap day three times every four hundred years. This led to the Julian calendar gradually running out of sync with the seasons. The more accurate Gregorian calendar was eventually introduced, missing out some dates altogether to set it back right. In England these were the eleven days between 2 and 14 September 1752. The same year the start of the year was changed from 25 March (Lady Day) to 1 January -- so 1751 only had 288 days, and 1752 only 354. The Treasury did not want to miss out on a whole year's tax, so the start of the tax year moved to 6 April, as it still is now -- "Old" Lady Day. For a long time afterwards dates were given as New Style or Old Style.

[Marsh]

Try http://webexhibits.org/calendars/calendar-roman.html#Anchor- 34108 This has more about calanders than I ever knew existed -blame the Babylonians!