system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do scientists say directions such as left/right and up/down don’t exist in outer space?

Lets say you took off in a little rocket ship from Texas, and you saw a cool star “behind” the earth. Isn’t that the direction you would go in? So thats left, right, up and down in space, no?
gpt
Not really. The concept of *behind* still makes sense, in a relative way (i.e. your ship A, earth B and cool star C are all aligned; someone at A could say C is behind B, or someone at C could say A is behind B).

However, once you leave earth's gravity well (or that of another suitably large object), there is no universal up/down/left/right. You could roll your ship 180 degrees while staying on course, and totally invert all those relative directions.