Equation of Time Complications
Not all complications are created equal, and some of them are more complicated than others. The equation of time is a seldom discussed complication, most likely due to its exclusivity. It should not, however, be dismissed as trivial, as it serves a very important function going back thousands of years.
Humans, being the feeble-minded creatures that we are, spend our lives pretending that a day is 24 hours long, however, due to the unusual shape of Earth’s orbit (an ellipse), days are actually 23 hours, 56 minutes, and 4 seconds long – on average. In reality they vary throughout the year reaching a minus of 16 minutes (so 23 hours and 44 minutes) in November, and a plus of 14 minutes (24 hours and 14 minutes) in February. Equation of time complications correct this discrepancy by calculating and displaying the difference between mean solar time and apparent solar time – that is, the difference between the time we usually refer to, in 24-hour intervals, and the actual time based on the Sun. Therefore, by referring to your equation of time complication you can see just how far off mean solar time is from apparent solar time, the only caveat being that the complication is based on the location/time-zone of the user (so if you were thinking of going to Bali for the next Vintage Rolex Asylum, you might want to consider bringing another watch).
Humankind's struggle to understand time has prevailed since ancient Mesopotamia, when sundials and their variants were our primary tools for time measurement. As time keeping became more accurate, apparent solar time was replaced with mean solar time, with cities like Geneva and Berlin officially adopting mean solar time in 1780 and 1810, respectively. Today it may be considered impractical to worry about true solar time, but to time nerds like us, it is essential. And although it is rarely seen as a stand-alone complication, the equation of time truly stands alone; as an astronomical tool and a beautiful piece of horology.