Following the Sunstone

Vikings made long open-sea voyages when most European cultures were sticking close to the coasts. This allowed them to reach Iceland, Greenland, and even the tip of North America. But this was long before magnetic compasses. How did they navigate, especially in the North Atlantic, where the sun may stay below the horizon for months at a time or be hidden by clouds?

Norse sagas make reference to something called a “sunstone” which enabled navigators to find the sun when the sky was overcast. An interesting thing is that there is something kind of like this which exists and was…