According to https://www.seis-insight.eu/en/public-2/seis-instrument/rweb


Around the handle is a small sundial, which enables geophysicists to estimate the azimuth— i.e. the orientation of the seismometer with respect to the Red Planet's north pole—using their knowledge of the seismometer's location on Mars and the time at which the direction of the shadow is measured.

Question: How many sundials & Sun compasses are there on solar system bodies? Or at least those placed by humans?

I'm also interested in things that were not primarily or originally designed to be sundials, but have been used in such a way that the orientation of a shadow has been used to determine the direction of the Sun, or the position/orientation of the object.

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below: A photographic up-side-down "top down" view of the actual sundial. From: https://spaceflight101.com/insight/photos-insight-mars-lander-undergoes-assembly-testing/

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The sun compass (letter G) in the image below is from What are these structures on the Lunar Ranging Retro Reflector (LRRR) arrays for?, annotated, from here.

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  • 3
    $\begingroup$ The Marsdial was designed for Spirit and Opportunity, and a spare was used on Curiousity. Partial credit goes to Bill Nye. $\endgroup$
    – amI
    Nov 27 '18 at 10:26
  • $\begingroup$ @amI yes, I remember hearing him mention something about the inspiration coming from Nye's father in an interview several years ago. $\endgroup$
    – uhoh
    Nov 28 '18 at 4:44
  • 1
    $\begingroup$ I wonder if the idea was original or influenced by observing shadows on the Viking camera calibration targets. Warning - searching Viking Sundial will take you to a whole different controversy. $\endgroup$
    – amI
    Nov 28 '18 at 7:44

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