Longitude Solar Noon Shift

• two locations at different longitudes or two trustworthy observers
• clock or phone time
• simple vertical stick or gnomon
• sunny conditions near local noon

1. At each location, track when a vertical stick casts its shortest shadow.
2. Record the local clock time of that shortest-shadow moment.
3. Compare the measured time difference with the longitude difference between the two sites.

This visual shows the core geometry the experiment is testing before the real-world observation is made.

• Two locations east and west of each other do not reach local solar noon at the same clock time.
• The difference scales in the expected direction with longitude separation.
• The shortest-shadow moment is tied to solar geometry rather than to arbitrary map artwork.

That repeatable time shift supports a rotating globe with longitude-based solar timing.

• NOAA Solar Position Equations: Published solar-position equations behind noon-angle and longitude-time tools on this site.
• U.S. Naval Observatory: Sunrise / Sunset Tables: Primary ephemeris tables for comparing local solar noon timing between longitudes.
• USNO: Solar Noon Data: Official solar-noon timing service used to verify the ~4 minutes per degree of longitude shift.

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