system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: if the earth moves at over 60k MPH, why does it appear slow to astronauts? Is everything relative to the universe moving? And if so, how fast are you really going when floating in space at a standstill?
gpt
Because the astronauts are also moving at roughly the same speed in the same direction, they only notice the speed difference. 

There is no telling how fast you are absolutely moving in space, as we can only measure it relative to something else. The only truly set speed is the speed of light. But due to special relativity even that can't be used to measure absolute speed.