[TaylorAlexander]

Realistically GPS is the answer, but it’s notable that you could also use a simple light sensor combined with accurate clocks to get your position on earth:

https://en.m.wikipedia.org/wiki/Light_level_geolocator

[vmfunction]

> Recording light levels over time Wonder how much time is needed to determine location.

[TaylorAlexander]

You just need to determine the time of sunrise and sunset relative to a known location and you get a rough idea of latitude and longitude.