Which function allowed medieval astronomers using astrolabes to determine the time of day from star positions?

💡 Explanation

Stereographic projection enabled mapping of celestial sphere positions onto the astrolabe's flat plate, because this transformation preserves angles. Therefore, time can be inferred via relative star positions, rather than relying on telescope, cycles, or expansions.

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• Within ancient Roman fortifications, which consequence arises from excessive mortar thermal expansion?
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