People have been using the sun, moon and stars to help them find their way for a very, very long time.

And not just people but other animals too – like birds, moths and beetles – to name but a few. This is a really exciting area of research and new discoveries keep piling in, many of which are described in Incredible Journeys.

Eric Warrant and Marie Dacke, for example, have shown that nocturnal dung beetles roll their carefully sculpted dung balls back to their nests using the light of the moon or the Milky Way as a guide.

And recently Eric Warrant and David Dreyer have shown that the Australian Bogong moth also makes use of the Milky Way to maintain a steady course on its 1000 km migratory journeys (as well as a magnetic compass).

We know that many birds that migrate by night orient themselves by paying attention to the rotational pattern of stars around Polaris, which marks the direction of true north.

My guess is that our prehistoric human ancestors would also have been pretty good at this kind of celestial navigation - tens of thousands of years ago.

What we know for sure is that the builders of Stonehenge and many other ancient monuments around the world are carefully aligned so as to highlight key celestial events like the summer and winter solstices – that mark the longest and shortest days of the year.

And the amazing Nebra Sky Disc – discovered in Germany in 1999 – suggests that our Bronze Age forebears understood the very complicated relationship between the solar and lunar years. It was made about 3,500 years ago. http://www.bibliotecapleyades.net/arqueologia/nebra_disk.htm

And the Greeks knew a thing or two. The amazing Antikythera Mechanism – discovered by sponge divers over a hundred years ago – dates from around the end of the 2nd century B.C. It’s by far the most sophisticated mechanical device yet discovered from the ancient world. The Antikythera Mechanism seems to be a complex mechanical “computer” which tracks the cycles of the Solar System: https://en.wikipedia.org/wiki/Antikythera_mechanism

We know frustratingly little about how the Greeks and Romans navigated at sea, though they travelled widely - and not just in the Mediterranean. It’s always assumed that they didn’t use any specialised equipment. But the Antikythera mechanism makes you wonder…if they knew that much about the behaviour of the heavens, would they not have put their expertise to navigational use?

On the other side of the world the islanders of the Pacific were already starting to venture out across the Pacific at least two thousand years ago. In their ocean-going sailing canoes they could make accurate landfalls on small islands after travelling as much as two thousand nautical miles across the open ocean.

They didn’t use any instruments or even charts. They relied only on their wits and finely-tuned senses – and a lengthy apprenticeship that started when they were children. When western sailors like Bougainville and Cook first encountered these navigational prodigies in the mid-18th century they were astonished.

Luckily we know a lot about how the Pacific Islanders navigated because, back in the 1960s, researchers started asking the right questions - before their extraordinary skills had completely died out.

At the heart of traditional Micronesian and Polynesian navigation was an encyclopaedic knowledge of the sky. The master navigators knew exactly where on the horizon 32 bright stars rose and set, and they could steer a steady course by reference to them. They also understood that Polaris indicated where true north lay and during the day they could steer by the light of the sun by accurately allowing for the its gradual movement across the sky. They had many other remarkable skills and happily these are now being widely practised once more: http://hokulea.org

Before electronic aids like GPS arrived on the scene, navigators everywhere learned to observe the world around them very closely. The colour of the water and its depth, the composition of the seafloor (tested with a lead-line), the behaviour of birds, the shape and colour of clouds – these and many other signs could give early warning of the presence of land, often long before it could be seen.

In former times, sailors everywhere paid the closest attention to the world around them - as well as the skies above them. Safe navigation depended on complete immersion in the natural world. It may not always have been as safe or reliable as navigating by GPS, but it was a far richer and much more rewarding experience. And it was also a great deal more robust: no problems like flat batteries, solar storms, spoofing or jamming!