Each piece represents a fraction of the day. The largest represents a ½ day (2 -1 ), followed counter-clockwise by ¼, ⅛ th and so on. The smallest time interval represents 2 -16th of one day (about 1.318 seconds).
You can't (easily). So what's the point? To look at time as divisions of a day. When an interval passes, it transitions to up (it is "on"). For example, after half a day, the 2 -1 will be up and you can tell it's past noon. Evening (6pm) would be denoted by the left two indicators (2 -1 and 2 -2 ) being active.