The Earth Standard Day (ESD) is a standard time unit that denotes the length of one day to be relative to Earth's axial rotation. Consequently, one ESD is equal to 24 hours. This unit is needed to resolve day length discrepancies between the various planets and moons inhabited by humanity, both across the Sol system and outside.
- Please note that no such unit of time measurement has ever been referenced in either the book and TV series, but it is assume that some similar convention must exist to allow for the resolution of any measurement discrepancies.
- An unexplained acronym (SSTC) for time measurement was featured in the TV episode " Cascade", but as of now, what it represents is unknown.
- Also what does SSTC (rel) mean, as found in the lower right-hand side? Is it like UTC (Universal Time Coordinated), which is another way of saying Greenwich Mean Time (GMT).
- Does SSTC mean Sol System Time Coordinated, or Sol System Time Code? What about rel, does it mean relative, as in the time is adjusted for the local region and SSTC is the standard of time which is agreed upon. For reference, consult the British Standard & Practices concerning Railroad Standard Time and subsequent American adoption.
- Railroads are responsible for implementing timezones in North America. So many trains sharing the same track, timing was crucial, miscalculations were fatal. In 1883, Railroads impose timezones to write timetables that could effectively manage their tracks.
- A standard of time is needed with respect to the fulfillment of contracts, and scheduling commitments.[Citation needed]