it's nighttime in the Australian Outback and it's dark very dark but if you look up the sky is a blaze with light we're looking towards the heart of the Milky Way galaxy a vast pin wheel of about 100 billion stars can you see the Emu yeah that's the one it's made of dark clouds of dust and gas obscuring the lighter parts of the sky there are several legends about how the Emu was banished to the heavens but in the Aboriginal nation of wajer her position in the sky signals the time of year best for collecting
emu eggs for most of human history understanding the sky was not The Preserve of scientists but a precious tool for our survival for building cultures religions and societies and in some places it still is this is Orion the hunter you're probably familiar with his belt and sword but if you're close to the equator it looks a lot more like a canoe a thousand years ago the Polynesians were the most accomplished Navigators in the world up to the 11th century they explored over 1,000 tiny Islands scattered across the Pacific Ocean one of the ways they did
this was by using an ingenious memory technique with a stone canoe built on the beach a trainy navigator would face the sea and sit in there night after night memorizing the rising and falling positions of the Stars when the crew was ready to depart they would head for a star near the Horizon switching to a new one once the first either Rose or set as it moved across the sky each sailing route required a specific sequence of stars like a password or a musical Motif Celestial navigation using the sun moon and stars to work out
precisely where you are in the world was essential to European seaf farers too [Music] but what if it wasn't a navigation tool you were after but a way of judging time some have suggested that Stonehenge in England was built as an astronomical computer of great sophistication capable of predicting eclipses this can't be proven it's most likely to be a precise is way of determining the winter solstice perfect for timing observances around the shortest day of the year Stonehenge is solstici aligned meaning if you're approaching the entrance from the Northeast the sunset at midwinter will cut
the monument neatly in half new Grange in Ireland does an even better job a 19 M passage runs the length of a long Barrow leading to a central chamber in the mornings around the winter solstice The Sun Shines directly in through a crack above the doorway new Grange was a tomb so for the people that built it ancestors death the Sun and seasonal renewal were probably linked perhaps it was the job of the ancestors to turn the sun around at midwinter guaranteeing the return of spring one of the most stunning examples of an ancient astronomical
tool is at janio in Peru a line of 13 Towers provided a detailed solar calendar to someone viewing it from a specially built doorway people may have gathered from miles around to celebrate certain days of the year [Music] but with the development of complex Technologies such as GPS most humans no longer rely on the sun moon and stars to travel or to organize their lives just as well because light pollution is increasing globally between 2 and 10% year on-ear only one in five people in Western Europe and America can now see the Milky Way but
birds need the Stars including the North Star to navigate if they can't see them due to light pollution from cities they run into trouble denying animals access to the stars is just one of the many ways in which light pollution impacts nature but that's another story Reliance on the sky as a Guiding Light is not uniquely human but perhaps our use of the sky to find food to organize our lives to socialize to pray was not just something we did before better technology became available perhaps it was what made us who we are [Music]
