Mars is divided into 11 time zones, denoted by MTC-5 to MTC+5. “MTC” denotes Coordinated Mars Time, the Martian equivalent of UTC (Universal Coordinated Time). Some “friendly” names and codes for the time zones are suggested, based on the dominant areographical feature in each time zone.
| Time zone | Western edge longitude | Eastern edge longitude | Friendly name and code |
|---|---|---|---|
| MTC-5 | -180° | -162° | Amazonis Time (AMT) |
| MTC-4 | -162° | -126° | Olympus Time (OT) |
| MTC-3 | -126° | -90° | Tharsis Time (TT) |
| MTC-2 | -90° | -54° | Marineris Time (MT) |
| MTC-1 | -54° | -18° | Argyre Time (AGT) |
| MTC | -18° | 18° | Noachis Time (NT) |
| MTC+1 | 18° | 54° | Arabia Time (ABT) |
| MTC+2 | 54° | 90° | Hellas Time (HT) |
| MTC+3 | 90° | 126° | Utopia Time (UT) |
| MTC+4 | 126° | 162° | Elysium Time (ET) |
| MTC+5 | 162° | 180° | Arcadia Time (ACT) |
As you may guess, a time zone’s number, from -5 to +5, tells you how many decisols to subtract from, or add to, MTC to find the local time. It couldn’t be simpler.
MTC-5 and MTC+5 are 18° wide. All other time zones are 36° wide. MTC-5 and MTC+5 are separated by the Mars Date Line (MDL), which coincides with longitude ±180°.
When travelling east, you would add one decisol (100 millisols) to the local time upon entering a new time zone, except for when crossing from MTC+5 to MTC-5 across the MDL, in which case you would subtract 1 sol from the local date.
Conversely, when travelling west, you would subtract one decisol from the local time upon entering a new time zone, except for when crossing from MTC-5 into MTC+5 across the MDL, in which case you would add 1 sol to the local date.
To find the centre longitude of any time zone other than the edge cases of MTC-5 and MTC+5, multiple its number (from -4 to +4) by 36°. To find the western boundary longitude subtract 18°, and to find the eastern boundary longitude add 18°.
There is no daylight savings on Mars. Daylight savings was never a very good idea and causes a lot more problems than it solves.