So I did a degree some time ago and after watching a programme on TV, I decided to revisit relativity and set myself some questions. One of these was the time difference by spending time on the space station. I worked out that roughly for every 15 mins that pass, the time difference will be 1 min, or after 3 months there will be a difference of just over 6 days. My question is: For Who? Being on Earth, the space station is moving relative to us so if we could observe the clock on the station, it would run 1 min slow after 15 mins. But then being on the space station, the earth is moving relative to it, so one would assume that the same would apply, that observed from the station, the clock on earth will run slow. But clearly one clock will be faster than the other when brought to the same location and compared side by side. So whose clock really runs slow? Late night thoughts that will keep me up for even longer!