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Activities & Downloads

Sundial Trivia Quiz

Test your gnomonic knowledge with an original quiz based around instrument classification

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Print and assemble this lunar volvelle, and turn your sundials into moondials! This downloadable kit includes versions with and without directions

Note that this volvelle cannot be used with altitude dials.


To use, rotate the arrow index to the hour indicated on the dial by moonlight (12 am is located at the bottom of the scale; 12 pm at the top). Next, read off the true solar time indicated by the current lunar age mark (number of days since the last new moon).

Lunar Volvelle

Equation of Time

Download the official BC Gnomonics equation of time! Intuitive labels allow an easy conversion from local apparent time to mean time.


To go all the way to civil time, add the appropriate longitude correction for your location (see LAT to Civil Time).

Also available is an alternate design, more in line with the US Naval Observatory's current definition.

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Equatorial Ring Dial

Print and assemble this simple, two piece equatorial ring dial, and find true solar time with impressive accuracy! While using sturdier materials such as cardstock results in a higher degree of stability and accuracy, simple paper offers a functional, if ephemeral dial.


After cutting out the dial, fold out its three components so that they rest perpendicular to each other. Suspending the dial from the latitude of use allows true solar time to be read from the equatorial ring.

Rotating the dial so that the upper half of the nodus beam falls on the top of the hour scale will result in the most accurate readings.

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