Flutterby™! : Thoughts on dates 2010-08-30 16:34:03.427226+00

Thoughts on dates

2010-08-30 16:34:03.427226+00 by Dan Lyke 2 comments

Weekend Testers: Some thoughts on dates:

Now, how would you like to know that the days of a given month could vary by a day or two one direction or the other, and a committee met fairly regularly to determine where and when the days will be each year (or to be closer to accurate, each decade) and the basic rules from the past were applied, but there was no guarantee that those days would replicate? Welcome to the Nepali calendar, which is based on the Hindu Bikram Samwat calendar. This calendar is a "lunar-solar" calendar, which means that keeping it in sync with the lunar cycles is just as important as is keeping it in sync with the solar cycles. This makes for a much more dynamic calendar, with many more rules as to how many days each month has and when they are applied.

Cool, in a freaky "wait, there are computer-using cultures that don't have enough arithmetic or astronomy to make deterministic calendars yet?" sort of way.

Beats my time/calendar headaches.. I have been tinkering with flot and while I like it's display functionality, doing date/time representations in JavaScript is a pain compared to doing it in MySQL and just displaying the results with whatever.

Any lunar calendar has this problem innately, but most people aren't particularly aware of it because they don't come into contact with calendars which haven't already standardized on an adjustment (eg. the Gregorian calendar, where no one really ever asks why some months have more days than others, and no one but scientists and calendar geeks remember that you lose three intercalary days which would normally occur in every 400-year cycle).

The Jewish calendar has a varying adjustment but it follows fixed rules - there is a pattern to when some months in it get extra days, and it's fairly complex. Nobody who doesn't need the Jewish calendar for religious observances cares. I could go look up the rules (I did once, back when I did an essay about it) but you don't care either.

The only significant lunar calendar I can think of still in use which is not adjusted in any way is the Islamic calendar, which drifts freely across the solar year, which is why Ramadan is at a different time of the Gregorian year every year. It was precisely because they wanted to avoid this drift (for example, it was important to the initial users of the Gregorian calendar to keep Easter the correct distance from the vernal equinox) that most of the world's lunar calendars have gotten standardized to a solar year.