This 24-Hour Sundial Brings Its Own Sun — So You Can Tell The Time at Night

Maker D. Bishop has solved an engineering puzzle thousands of years old, by creating the first sundial that works even at night — sort of.

"According to Wikipedia sundials are among the oldest form of time telling invented," Bishop explains. "Our oldest example comes from Egypt 3,500 years ago. Unfortunately a sundial only works when the sun is up. You may be asking yourself, what if I want to tell time at night? Until now this was not possible with a sundial."

A sundial, as the name implies, needs the sun to work: properly aligned, a pointer on the top casts a shadow that moves along the face to indicate the current time based on the position of the sun in the sky. No sun, no shadow — which means nightly timekeeping was guesswork until the invention of less sun-based time-tracking devices.

Bishop's 3D printed sundial solves this centuries-old problem a modern way: by bringing its own sun, in the form of an LED on an arm connected to a servo motor. This, in turn, is connected to an Arduino UNO development board and a real-time clock (RTC) module — something, sadly, the ancient Egyptians lacked. As the time ticks, the arm turns causing the shadow to shift along the face of the sundial — delivering a night-ready sundial at last.

The project is documented on Instructables, including source code and the STL files for printing the sundial itself.