Mars sol

A series of photographs in succession show the Sun rising above the horizon as the atmosphere becomes brighter

Sunrise on Mars

A series of photographs in succession show the Sun sinking below the horizon as the atmosphere becomes darker

Sunset on Mars

Images captured by InSight

Sol (borrowed from the Latin word for sun) is a solar day on Mars; that is, a Mars-day. A sol is the apparent interval between two successive returns of the Sun to the same meridian (sundial time) as seen by an observer on Mars. It is one of several units for timekeeping on Mars.

A sol is slightly longer than an Earth day. It is approximately 24 hours, 39 minutes, 35 seconds long. A Martian year is approximately 668.6 sols, equivalent to approximately 687 Earth days^[1] or 1.88 Earth years.

The sol was adopted in 1976 during the Viking Lander missions and is a measure of time mainly used by NASA when, for example, scheduling the use of a Mars rover.^[2]^[3]

^ "Mars' Calendar".
^ Snyder, Conway W. (1979). "The extended mission of Viking". Journal of Geophysical Research. 84 (B14): 7917–7933. Bibcode:1979JGR....84.7917S. doi:10.1029/JB084iB14p07917.
^ Allison, Michael; Schmunk, Robert (30 June 2015). "Technical Notes on Mars Solar Time as Adopted by the Mars24 Sunclock". Goddard Institute for Space Studies. National Aeronautics and Space Administration. Retrieved 13 June 2018.

[Mars'_Calendar-1] "Mars' Calendar".

[Snyder_1979-2] Snyder, Conway W. (1979). "The extended mission of Viking". Journal of Geophysical Research. 84 (B14): 7917–7933. Bibcode:1979JGR....84.7917S. doi:10.1029/JB084iB14p07917.

[NASA.Notes-3] Allison, Michael; Schmunk, Robert (30 June 2015). "Technical Notes on Mars Solar Time as Adopted by the Mars24 Sunclock". Goddard Institute for Space Studies. National Aeronautics and Space Administration. Retrieved 13 June 2018.

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