THE DARIAN SYSTEM
1.0 The Darian Calendar for Mars
2.0 The Calendars of Jupiter
3.0 The Darian Calendar for Titan
The Darian calendar is a complete timekeeping system for the 24-hour, 39-minute, 35.244-second sol and the 668.5907-sol vernal equinox year on Mars. Features include:
Moving beyond Mars, two systems of calendars for the four Galilean satellites of Jupiter are explored, one based on the terrestrial year and one on the Martian year. The orbital periods of the moons are divided into "circads" of approximately 21.3 hours. The relationship of the orbital periods of Io, Europa, and Ganymede leads to the adoption of eight-circad weeks. The natural cycles of the Galileans leads to a 13-month calendar based on the terrestrial year and a 24-month calendar based on the Martian year. Not only is 13 a prime number, which is inconvenient for subdividing the year into smaller cycles, but a 13-month calendar deviates considerably from the 12-month Gregorian calendar, thus commonality is lost. On the other hand, the Martian-year option represents less deviation from the Darian calendar. Thus, the Darian system is the preferred solution for the Galileans. Intercalation formulae out to 10,000 Martian years are provided, as well as epochs for calibrating this set of four Galilean calendars to the Darian calendar for Mars.
Finally, a timekeeping system for Titan based on the Darian system is explored. The orbital period of Titan is divided into 16 "circads" of approximately 23.95 hours. As with the Galileans, the relationship of the orbital period of Titan to the circad leads to the adoption of eight-circad weeks. The Martian vernal equinox year is used as the basis for Titanian years. Years are divided into 24 months, nominally containing 28 circads (four weeks), with rules for lengthening the months to 32 circads (4.5 weeks) as necessary. Common years contain 688 circads, and leap years contain 696 circads. Intercalation formulae out to 10,000 Martian years are provided, as well as an epoch for calibrating the calendar to the Darian Martian calendar.