Most cultures have a tradition of using the night sky to help them travel; stars can point the way on land as well as at sea. Mariners and explorers relied on celestial navigation, the ancient technique of using the Moon, stars, and planets to find their way. The skill of using stars for navigation remained virtually the same for millennia until 18th century instruments honed the measurements taken from the sky.
To use the skies, the navigator needed to assume that the Earth was at the centre of the universe, with all stars and planets moving in relation to it. We have learned that the Earth actually orbits around the Sun, but that concept does not change how human navigators perceive stars. Some stars appear to be “fixed.” The Assyrian Empire, which ruled in the Middle East until 612 BCE, depicted the star Polaris in its artwork. Polaris, the “North Star,” is actually a group of three stars that appear to remain positioned over the Earth’s northern pole. Polaris has guided shepherds, the indigenous people of North America, and mariners from Ancient Egypt and back as far as prehistoric times.
In much of the southern hemisphere, Polaris cannot be seen, but a constellation known as the Crux or Southern Cross points in a similar way to the southern pole. It is known by the Maori of New Zealand as “The Anchor.” Such markers helped the Polynesians, talented navigators who sailed great distances. The Polynesians travelled the Pacific using stars on the open sea and the movement of birds and cloud formations when nearing land. They created detailed charts with winds and ocean currents represented by sticks tied to shells that indicated Pacific islands.
The Vikings of Scandinavia relied on coastal navigation, generally remaining within sight of land. Their use of celestial navigation included the stars and the Sun. According to archaeological evidence from Greenland, they developed the Viking “Sun-compass.” Designed as a rotating disc, the compass picked up the hyperbola or curve caused when it was struck by the rays of the Sun. Direction could then be determined using the markings that divided the disc into sections.