Chris Hadfield took 45,000 photos while he was in space.
He told Quartz that he'd been struck by the fact that a lot of people on social media had asked him to take pictures of their hometowns.
He told the site: “To me that was delightful. At first I thought how narcissistic. But then when I thought about it, it struck me for two different reasons: people are proud of where they are from."
"And they have an ache and a desire to see how they fit in with everything else. It’s a dawning self-awareness, like seeing yourself in a mirror for the very first time, but on a global scale.”
He somehow managed to whittle the thousands of images down to 192 for his new book.
He told CBC: "I wanted it to be as if the two of us were floating weightless in the copula and I was pointing to something with you. I wanted it to feel that way, because to me, that’s what really matters."