So time in SL is funny in various ways. First, there’s SLT, Second Life Time or Standard Linden Time or something, which is the same as United States Pacific Time (and presumably gains and loses an hour due to daylight savings at the same times as whatever jurisdiction Linden Lab’s headquarters is in does). SLT is very useful for co-ordinating things, because people in SL are from at least as many different time zones as exist on Earth, and while having a single time-scale in common doesn’t make it any easier to get to those events that happen at 2am local time, at least you know they’re at 2am, and don’t try to attend at some other time entirely because you used the wrong GMT offset to convert from Irish to Japanese times.
As well as SLT, we also have sun time. On the mainland, and on any private estates where the estate owner hasn’t overridden the sun, and as long as you yourself haven’t overridden the sun position in your viewer, you’ll see (if you’re outside, or in a place where the ceiling is missing or transparent, or if you’ve cammed out of doors) the sun (or the moon) going around from East to West, just like in the atomic world.
But the SL default sun has a number of features that are very unlike the atomic world. In the atomic world, the sun rises roughly every 24 hours. In SL (assuming, etc), there’s a sunrise every four hours. So the sun-day is just four hours long; there are six sunrises and six sunsets every SLT-day. (Did Linden Lab do this so there’d be more scenic and romantic times? Or just on a whim? Or by accident? Who knows!) When it’s midnight SLT it’s also midnight according to the sun, but byond that things get strange.
The four hour sun-day isn’t split into two hours of daylight and two hours of night; in fact the daytime is three hours long, and the night is one hour long. So midnight is half an hour after sunset, whereas noon is 90 minutes after sunrise. (The moon is also locked directly opposite the sun; so the moon is always at its zenith at midnight, it sets at dawn, and rises again at sunset.)
To illustrate all this, I made a clock (see illustration at right or somewhere). It occurs to me, having just uploaded the picture, that being a completely static picture of a circle with three hands and a little mark at the top, it doesn’t actually tell you anything at all except “look! a clock!, but there you are.
What the clock actually does, in SL, is map the SL sun-day into a 24-hour clock day. At sun-midnight (when the moon is high), all three hands point up. The hour hand goes around twice per sun-day (that is, twice every four hours, once every two hours), just like an atomic-world twelve-hour clock goes around twice per atomic-world day.
The minute-hand goes around twelve times during each daylight period, and twelve times during each nighttime period (and the secondhand does the same only sixty times faster), just like (roughly) in the atomic world. Since the SL sun-day daylight period is one-third the length of the nighttime period, the hands move three times as fast at night.
Which is to say, I made a clock that moves four times as fast as an atomic-world clock when the SL sun is up, and twelve times as fast as an atomic-world clock when the SL sun is down. So that you can see that, when you’re out partying under the SL stars, one precious minute is passing away every five seconds. Which is just what it feels like sometimes! :)