British astronaut Tim Peake will become the first ever person to take on a marathon while in space - when he competes in the 'London Marathon'.
The astronaut from Chichester in West Sussex will begin at exactly the same time as runners in London on April 24th, but he will be tethered to a treadmill on the International Space Station as it orbits earth.
Peake will run the 26.2 miles while watching an HD video of the iconic London course on a big screen in front of the treadmill. He is a keen runner and completed the London Marathon - on earth - in 1999. This year he is running in space to raise awareness of the Prince's Trust.
He will have to wear a harness to push his body down onto the treadmill because of the low gravity on the International Space Station.
Peake will become the first British astronaut in space when he launches from Baikonur, Kazakhstan on Wednesday 17th December.
The HD video of the London Marathon has been developed as part of a virtual experience app, to let runners around the world 'take part' in the famous marathon while on their own treadmills.