Comment on How accurate can your position be calculated from a photo of the sun you post online?

dhork@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

Latitude can theoretically determined by the data in your picture. Longitude is much harder, because you can’t really tell how far east and west you are based on the angle of the sun alone. This was a historic problem, especially when mankind started traveling across oceans.

The problem can be solved by knowing your time relative to some reference point. This is how Greenwich Observatory became so important to timekeeping: to determine longitude, ships had to carry a good clock that showed them what time it was at Greenwich, and the difference in time between when the sun was directly overhead on the ship and noon at Greenwich told them their longitude.

So, the main piece of information that gives away your latitude is actually the time, assuming it is either stored as UTC or as local time with a UTC offset…

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