2  Martian Calendars

We only provide the Darian calendar in this intial version, but additional calendars maybe added depending on requests.

2.1 The Darian Calendar

In Earth time, a Martian sol (day) is 24-hour, 39-minute, ~35.244 seconds and the year is ~668.6 sols. To account for this differences, the Darian Calendar [1] defines the following:

  • Seconds: 1 a Martian second is ~1.0275 Earth seconds (~2.75%) longer.
  • Minutes: 60 Martian seconds per minute.
  • Hours: 60 Martian minutes per hour.
  • Sols: 24 Martian hours per day.
  • Weeks:
    • In 28-sol months: Seven-sol weeks only.
    • In 27-sol months: The final week has six sols.
  • Months: 28 and 27-sol months.
  • Years. 24 months per year. The calendar year begins on the vernal equinox. A year is either 668 (common) or 669 (leap) sols, depending on leap-year rules.
    • 668 sol years: 20 months of 28 sols and four months of 27 sols (one at the end of each quarter).
    • 669 sol years: the last month of the year (which also ends the fourth quarter) is a normal length of 28 sols rather than 27.

2.1.1 Leap year rules

  • Even-numbered years are 668 sols, except years divisible by 10.
  • Odd-numbered years and multiples of 10 are 669 sols.
  • Every year divisible by 100 is 668 sols (extra correction).
  • Every year divisible by 500 is 669 sols (extra correction).
  • This scheme keeps the calendar error at only ~1 sol in 10,000 Martian years.
  • Intercalation formula: \((\mathrm{Y}-1) \backslash 2+\mathrm{Y} \backslash 10-\mathrm{Y} \backslash 100+\mathrm{Y} \backslash 500\).

2.1.2 Names of the days of the week

The following names for the days of the week on Mars are introduced.

  • Sol Solis (Defined as the first day of the week)
  • Sol Lunae
  • Sol Martis
  • Sol Mercurii
  • Sol Jovis
  • Sol Veneris
  • Sol Saturni

While, to avoid confusion, people on Mars would call Earth days as follows:

  • Dies Solis (Sunday)
  • Dies Lunae (Monday)
  • Dies Martis (Tuesday)
  • Dies Mercurii (Wednesday)
  • Dies Jovis (Thursday)
  • Dies Veneris (Friday)
  • Dies Saturni (Saturday)

2.1.3 Names of the Months:

Twelve months bear zodiacal constellations Latin names and the other twelve the Sanskrit names for these same constellations. Sanskrit names appear in the calendar following its Latin counterpart:

  1. Sagittarius
  2. Dhanus
  3. Capricornus
  4. Makara
  5. Aquarius
  6. Kumbha
  7. Pisces
  8. Mina
  9. Aries
  10. Mesha
  11. Taurus
  12. Rishabha
  13. Gemini
  14. Mithuna
  15. Cancer
  16. Karka
  17. Leo
  18. Simha
  19. Virgo
  20. Kanya
  21. Libra
  22. Tula
  23. Scorpius
  24. Vrishika

2.2 Other Calendars

Additional calendars maybe added in the future.