American astronaut Scott Kelly grew two inches while spending nearly a year aboard the International Space Station.
The reason: his spine lengthened because there was no gravity in space to compress it, NBC News reported.
Kelly said he "feels pretty good" and will have his health monitored for the next year as part of an effort to learn more about how long periods in space affect a person's body, mind and spirit.
The assessment will include comparing Scott to his twin brother Mark, a former astronaut who spent the last year on Earth. This will help researchers detect any genetic changes that may have occurred in Scott during his long stay in space, NBC News reported.