oh-myyy-ribbon
(Photo by NASA via Getty Images)

For 340 days, the world looked up to astronaut Scott Kelly as he documented his innovative year aboard the International Space Station (ISS). Kelly shared spectacular images and even some thank-you notes from 240 miles above the earth.

But Kelly's time in space was anything but fun and games. He was a crucial half of the two subjects of NASA's Twin Study.

Keep reading... Show less