I've seen several planet in an alien sector, filled to the max (fuel/org/equipment) created by a member of another corporation.

Is there any reason for this? Did the aliens fill it, or did they do it for some reason?

depends on what you mean by an alien sector, and if they're gold aliens. If it was created by the corp and the corp still had ownership when you landed then my guess would be that they did it, if it's created by the corp and claimed by somebody different it could be the person who has it claimed or the creator corp or an inertim owner. One last question would be if it was mobile.

well, the answer to this is this is kind of a bug that some people use, and some people look down upon. basically, you just pop a planet in alien space and they will claim it and fill it up for you
it has been discussed many times before, you can search old posts for it if you want more info, or to see what people think about it.

Slim

Yes I look Down upon, its a bug in the game, an a exploit.
last game we corped, one of the members started to and i stoped him.
nex thing i know it was monkey see monky do, so for rest of game I found their planets in alien home space and layed a trap.
why play any game if you have to use cheatcodes, bugs, exploits.
Learn the game the the way it was designed to be played.
cheaters never win, and winners never cheat.[V]