In 1960 Joe Kittinger fell to earth from the edge of space and lived. Inside a pressure suit, attached to a huge helium balloon, Kittinger freefell from where the earth's atmosphere met space - an appalling, hostile, environment that would freeze us, and burn us and boil us away. It is the air that Kittinger fell through that makes our lives on earth possible - the atmosphere is made up of enfolding layers of air which protect us so completely that we don't even realise the dangers of space lurking just twenty miles above us. Gabrielle Walker's new book illuminates this most extraordinary and yet most underrated substance on earth: air. Thin air miraculously transforms into food; our atmosphere soaks up flares from the sun that are more violent than a nuclear explosion; the air wraps our planet in a blanket of warmth; radio signals bounce off a layer of floating metal in the air.