A year is a long time to spend circling the earth in zero gravity. In fact, we weren’t sure what spending that much time in space does to the human body, until now.

After a record setting residence aboard the International Space Station, NASA astronaut Scott Kelly has returned to earth after more than 500 days in orbit, two inches taller than his identical twin brother Mark.

One of the main goals of his record-breaking flight was to observe and study how well humans can endure in space. Currently, our understanding of how the human mind and body can cope on long-duration spaceflights is limited.

One of the unique advantages of sending Scott Kelly to space is that NASA was able to compare Scott with Mark, who spent the time with his feet planted firmly on the ground.

Upon return, Kelly, who spent more time in space than any other American astronaut, reports that overall he “feels pretty good.”

PQ: Kelly had returned to earth after more than 500 days in orbit, two inches taller than his identical twin brother.