| Since we are talking about dates and the like, I'd like to say a few words
about Julian. Calendars are a mess; of the hundred or so that have enjoyed some prominence somewhere somewhen, half a dozen are still in common use and translating among them is harder than figuring out the time in Delhi. Due to some quirks Mesopotamian mythology, all the survivors pretty much agree that a year has about 12 months, but they differ on the relation between months and moons, as well as how long a month is, when a month starts, when a year starts, what to do when the calendar gets out of synch with the heavens and what counts as out of synch. Calculating the time between to dates on any of these is a pain as well. Of course, there are cute little programs for doing this -- and translating between claendars as well (including some no one uses any more, like the Mayan?). Such programs use Julian dates for the various calendar dates, as do astronomers everywhere. A Julian date consists of the number of full dates and the fraction since 12 noon GMT on January 1, -4713 (a quirk of a different mythology). So, at the moment it is 2452099.52 and rapidly changing further fractions, corresponding to July 8, 2001, 19:32 CDT. And this time is 1) the same everywhere in the world, 2) given in a single system, not varying through bases 28,29, 30 or 31, 12, 10, 24, 60, 60, maybe 7, and take your pick -- in Julian precision is indefinitely extendable. 3) the system starts at 0 (the heretofore mentioned New Year's Day at noon), so all those muddles go. Of course, there are some down sides. The date looks long, although it contains fewer characters than a standard civil date: 07/08/01 -- but / looks short. And the time side is inconvenient (unless everyone used it), since (as is so often in time measurements) nothing correlates very well with hours, minutes and seconds. An hour is .041[6 of a day, so a minute is .00069[4 and a second .0000115[740. And, of course, there is no regular coordination between day numbers and natural phenomena, days of the week or whatever else might be important to farmers, mechants, priests, etc. etc. On the other hand, periodic astronomical events recur in regular ways, since they are at the base of the system. Hey! Captain's log: Star date---. |