Astronauts speaking to the pope from the space station - May 21, 2011
We can see how indescribably beautiful the planet is, they said. We can look down and see it is the most beautiful planet in the whole solar system.
"On the other hand, we can really, clearly see how fragile it is", said Ron Garan, a NASA astronaut serving as a flight engineer on the space station.
"The atmosphere for instance," he continued. "The atmosphere when viewed from space is paper thin, and to think that this paper thin layer is all that separates every living thing from the vacuum of space and all that protects us is really a sobering thought."