( 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 do n'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 . '' How high does the ISS orbit ? PN : We are 400 kilometers ( 248 miles ) above the Earth and fly at a velocity of 20,000 kilometers-per-hour ( 12,400 mph ) -- the equivalent of about 7.7 kilometers-per-second ( 4.8 miles-per-second ) . How did traveling to space change your outlook on Earth ? PN : `` I felt like a human being , a terrestrial guy -- not an Italian or a European . I felt like an earthling . `` You get an appreciation of how delicate the planet is . You see the atmosphere which covers the Earth like a blanket . It looked like if I would blow on it too hard it would float away . We know if that get 's corrupted in a certain way that 's the end . '' How do you think humans are affecting the planet ? PN : `` The impact we are having on this planet is surely microscopic when we look at one single event , but when you look at it and you repeat these events all over - a few miles across here , a few miles across there , a river here , a river there , a city here , a city there -- and it 's clear we are a major force in shaping the crust of this planet and its clear we have the capability of imparting changes . `` I can not say we are bad , or that we are causing the planet to go hot or cold . We do n't have enough data . But it 's clear that we are doing things that have a huge potential of making changes . We need to understand more . It 's a risky situation with a very delicate eco-system balance which can be dramatically skewed . '' Thoughts on the future of space travel ? PN : `` I think space travel will become successful as a tourism activity . I wish everybody could go up there and see the world from a different point of view , with different eyes . `` I would , for sure , send up the politicians ( some of them we should leave there ! ) to change the way they think , but I would also send up philosophers , journalists and theologians . ''
Italian astronaut captures amazing images of Earth from International Space Station . Paolo Nespoli used Twitter to send images back to Earth during a six-month mission which ended in 2011 . The ISS orbits 400 kilometers above Earth traveling at a speed of 20,000 kilometers-per-hour . April 22 marks the 42nd Earth Day with events being held all over the world .