A
Civilization advance.
The
sailors of antiquity studied the night sky, noting the positions and the movement of particular
stars. They realized that even when the shore was out of sight, they could steer by certain reliable stars. This crude, yet practical application of astronomy allowed the adventurous to sail into the unknown with a reasonable chance of finding their way.
Prerequisites: Astronomy and
Mapmaking.
Allows for: Physics and
Magnetism.