It was not supposed to be a photo safari. NASA took Scott Kelly into orbit aboard the International Space Station in March 2015 for a year so that scientists could learn what happens to the human body during long space missions. (A lot, as it turned out.)
But between the blood draws and the repairs of the equipment, Mr. Kelly directed a Nikon D4 towards the windows of the dome of the space station or, his favorite place, a porthole on the floor of a laboratory module.
A snowstorm on the east coast, the ethereal aurora, the deserts of Pantone in North Africa, the vast swirl of the Caribbean: Mr. Kelly captured everything and then shared it, turning Twitter into an eye on Earth . Many of the images are compiled in a book, "Infinite Wonder", published in October.
One day, the data obtained from Mr. Kelly's medical experiments can open the door to new worlds. His photos gave us an incomparable view of what we already have.