After spending an entire year in space, astronaut Scott Kelly is returning to Earth.

His identical twin, Mark Kelly, stayed grounded during the year, Nasa is conducting research on both men to see how a year of weightlessness affects the human body.

The research is critical as it will take a year of space travel to reach Mars.

While on the International Space Station, Scott Kelly shared fantastic images of our planet via Twitter and Instagram, as well as videos documenting every day life in space.

Edited by Olivia Lace-Evans. Produced by Sarah McHaney