Four-and-a-half billion years ago, Planet Earth was formed from a vast spinning nebula of cosmic dust, the detritus left over from the birth of the sun. Within the next 100 years, human life on swathes of the Earth's surface will end in a haze of heat, drought, and, again, dust. Dust is a legacy of 20th-century progress and a profound threat to life in the 21st century. And yet dust is something we hardly ever consider - it is so small and so mundane as to be beyond the threshold of thought. This book sparks curiosity and corrects that oversight.