Technically it is, we can defy physics in Ubox, I could make a star the size of a galaxy and I'm not even sure anything that massive exists, so adding thing's like city lights isn't too far a stretch, but if I remember right, GA said that they'd probably wont go that route but who knows, it might eventually be added in (don't shoot down a potentially good idea ) city lights do appear in game but are rare, I made quite a few planet's, very cold ones I might add, that had city lights on them that were rather densely packed I haven't had the patience to make a habitable world since alpha 12 so it might not be there anymore. A bug maybe?