Oddly enough, I was just reading that it's not possible to calculate the Islamic calendar in advance. Each month in the Islamic calendar begins when a new crescent moon is visible to a human observer; this varies with local conditions, including weather.

Okay, even more oddly, I just learned the same thing from -- was it Ben? -- this past weekend in Chicago.

So apparently, even if the culturally-constructed calendars aren't all running along the same lines, *some* kind of synchronicity is in motion here.

That's a really cool interface -- but also a kinda weird one.

The first weird thing I noticed is that the day-of-the-week track isn't the same kind of scale as the others. For the others, each track is conceptually "contained" in the previous one; day-of-week doesn't fit in that model.

The second weird thing is that the scales are kinda arbitrary. I thought it was interesting that each row has boxes of a different width (except minutes and seconds appear to be the same width), and I thought that was a direct consequence of the number of units on each row, but it's not quite: some of the rows have a little more than half their total number of units showing, some have a little less, and the year row has a completely arbitrary width.

So it's an artistically cool system, but looking at it from a Tufte perspective it's giving less (or at least different) information than it initially seems to be giving.

Good eye, Jed — hadn’t noticed that. It looks to me like the scale is something like “half the cycle fits on the screen,” with year being the odd one out. It is kind of misleading.

You can’t pre-calculate the traditional Islamic calendar, but there’s a rule-based variant (centuries-old, used by astronomers), called the tabular Islamic calendar, or Fatimid calendar; or you can fake it using historical data (Microsoft’s approach, the “Kuwaiti Algorithm”). Or so Wikipedia tells me.

the scale is something like “half the cycle fits on the screen,” with year being the odd one out.

Or, maybe the programmer knows something we don't, and the years will begin repeating in 2008.

Or time itself will start repeating. We might never know.