Sky Country by Karlie Noon and Krystal De Napoli review - Indigenous knowledge and understanding of the stars is astonishing

The next two chapters are the most interesting ones.

Gawarrgay, the Celestial Emu, is fully visible over much of the Australian winter sky - stretching from the Southern Cross, past the Pointers to the Scorpion and Sagittarius.

Indigenous observers used different shades of darkness as well as the outline of individual stars to define their emu.

The movement of the Celestial Emu throughout the year reflects the life stages of emus on the ground.

However, despite the comprehensive directions provided in Sky Country, an unpolluted-by-light sky is required for a true outline of this important figure to be realised.

During their 65,000+ years on the Australian continent, Aboriginal people witnessed one-off astronomical events - like supernovas - and noticed changes in stars that can only be detected by regular close observation - variation in size and colour of stars, slight changes in relative position of stars.

They recorded these events and changes in their stories and ceremonies. In more recent times, Western astronomers have determined the astronomical explanations for these events and changes.

Sky Country contains excellent descriptions of many basic principles of astronomy - descriptions that can be understood by readers with little or no knowledge of the field.

The authors write: "Monitoring seasons or the time of day, predicting the weather and navigating across large distances are just some of the ways that Indigenous people use holistic, observational knowledge."

Later chapters deal with way extraneous light is limiting the appreciation and study of the sky.

Sunlight being reflected to earth by the thousands of circling satellites and space junk is significant. Gas flares are also contributing to the problem.

However, there are individuals and organisations working to correct or at least limit pollution of the skies.

The large number of references in Sky Country to books, articles and academic papers encourage the belief that Indigenous astronomical knowledge is being carefully recorded and integrated into Western astronomical knowledge.

The narrative concludes with a fanciful, hypothetical letter from a 2044 custodian of planet earth to a current custodian.