Mars (MTC)
Sol count and clock for the Mars prime meridian
Mars keeps two counts that answer to our Julian Day and our clock. The Mars Sol Date runs continuously from 29 December 1873, one sol at a time, with no months or years to complicate it; Coordinated Mars Time is mean solar time on the Mars prime meridian. A sol is 24 hours 39 minutes 35 seconds, so a clock kept on Mars gains about forty minutes on ours every day — which is why mission teams who live on Mars time drift steadily out of step with everyone on Earth, starting work forty minutes later each day until they have gone right round.
In UTC at 02:02 on October 27, 2026, this calendar read MSD 54325.11726. The reading above is live, in your own time zone.
At a glance
- Type
- Another world’s clock and day count
- Origin
- Allison and McEwen’s system (2000), the one behind NASA’s Mars24
- Year
- About 668.6 sols — though this count has no months or years
- Day
- A sol: 24 hours 39 minutes 35 seconds
- Counts from
- 29 December 1873, for the sol count (the Mars Sol Date)
- Where it’s used
- Mars mission planning
- How it’s worked out here
- Allison and McEwen’s algorithm, as Mars24 uses it
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