Martian Dates

I'm not entirely sure why, but at some point I got it in my head to make up a calendar for Mars. The problem is that seconds and minutes don't add up to an even Martian day.

So I made up analogs to those units and gave them Latinesque names. Or maybe I looked up Latin equivalents. I can't remember, I wrote the initial version of this in 2006.

The initial conversion is from seconds to a punctum. All the other conversions up to months/lunes keep the same ratios as on Earth, so the net effect would be like if you had a clock that was running 2% slow.

1.0274875 seconds
60 puncta, 61.64925 seconds
60 minora
24 hora
37 sols (38 if lune number is divisible by 9)
18 lunes, 668 sols

Leap years wound up being a bit more complicated because the fraction isn't nicely close to ¼ like here. I added an end-of-year leap day on annos where division by 5 leaves a remainder of 0, 2 or 4, and the anno is not divisible by 50.

For sol names I stuck with mythology. For lune names I tried to pick things that were relevant to Mars. When I ran out of ideas I picked landers (yes, only the American ones -- I make no apologies) and then people who were important to space and science in general.


  1. Heliosol
  2. Deimosol
  3. Phobosol
  4. Terrasol
  5. Aphrodisol
  6. Zeusol
  7. Cronosol


  1. Percival
  2. Asaph
  3. Giovanni
  4. Wells
  5. Burroughs
  6. Mariner
  7. Viking
  8. Sojourner
  9. Odyssey
  10. Spirit
  11. Phoenix
  12. Sagan
  13. Bradbury
  14. Gagarin
  15. Shepard
  16. Armstrong
  17. Tereshkova
  18. Ride

Here are some dates I decided to convert. I'm not sure why I set the zero point to 1795 BCE any more, I know I wanted to always have positive dates and going that far back all but guaranteed that. I'm just not sure why I picked that particular point.

Today's date: Aphrodisol, Wells 33rd, 2030 22:27:13
E-mail format: Aph, 33 Wel 2030 22:27:13

2030-04-33M22:27:13 = +2024-06-25T05:27:47-04:00 (Current date)

0000-01-01M00:00:46 = –1794-01-01T00:00:00-00:00 (Martian Year Zero, Jan 1, 1795 BCE)

2000-01-01M00:00:00 = +1967-08-28T00:27:07-04:00 (Mars Y2K)

2001-01-02M23:06:24 = +1969-07-16T13:32:00-00:00 (Apollo 11 Launch)

2001-01-07M03:07:27 = +1969-07-20T20:18:00-00:00 (Apollo 11 Landing)

2017-04-22M23:20:08 = +2000-01-01T00:00:00-00:00 (Earth Y2K (UTC))

2025-18-39M00:00:00 = +2016-07-20T19:21:26-04:00 (Leap day example)

2025-18-39M00:00:00 = +2016-07-20T19:21:27-04:00 (Leap conversion example)