Moondial

Moondials are time pieces similar to sundials.

The most basic moondial is accurate only on the night of the full moon.

Every night after that, it loses on average[a] 48 minutes, while every night preceding the full moon it gains 48 minutes.

Thus, one week to either side of the full moon, the moondial will read 5 hours and 36 minutes before or after the correct time.

[citation needed] More advanced moondials include charts showing the exact calculations to find the correct time, as well as dials designed with latitude and longitude.

Moondial at Queens' College, Cambridge , showing the table of corrections for the phase of the moon