(CNN) - As an estimated one billion people around the globe take part in events to mark the 42nd Earth Day, Paolo Nespoli's images provide a striking reminder of our planet's awe-inspiring beauty and fragility as an eco-system.
During a six-month mission to the International Space Station (ISS) last year, the Italian astronaut snapped around 26,000 images, posting daily updates on Twitter.
"I really tried to capture what I was seeing. I was amazed by the response from people. It was very fulfilling for me. I was doing something which was very interesting for me, but it made me more happy that I could share the images," Nespoli said.
Nespoli explained to CNN what it's like to see the world "turning around your feet" and the unique perspective space travel provides on our planet and humans' collective impact on it.
Describe the view of Earth from space?
Paolo Nespoli: "It's a most unreal view you have from up there. It's look as though it's painted. One of the things you gain up there is an appreciation of planet Earth as a kind of ship. It looks like a ship flying in space.
"A lot of the time you're up there you are working so you don't have a lot of time to look out of the window. When you do, most of the time you see oceans and clouds - which is really nice.
"But it really takes a little bit of time before you acquire a perception of where you are and what you are looking at and how to look at it in the best way.
"After a month, a month and a half, something strange happens - you look out of the window and you know where you are. You might be over Australia, Africa, you just know. It's amazing how you just develop this."FULL STORY