Lauren Caldwell’s tribute to Giovanni de’ Dondi’s 1364 Il Tractatus Astarii, the first famous Astrarium, which is a mechanical planetarium that mimics the paths of the stars and planets. In other words, it's an astronomical clock Archimedes used a primitive model, but the first real working astrarium clock is credited to de Dondi. The backpiece here is the Mercury Wheelwork.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.