The 'scariest photo ever taken in space' has an incredible story behind it, as it captured an astronaut completely cut off from everything else.

This was the first untethered spacewalk in history. For 6 hours and 17 minutes, McCandless became a speck in the vastness of space; flying around with no cables to hold him from going loose.

Leonov’s walk on … On 18 March 1965 Soviet cosmonaut Alexei Leonov became the first person to leave a space capsule and, tethered to it, float freely in orbit – to space-walk.