there is actually a glitch where your comet will not be on the map and be in the "void" outside the screen
Viewing post in Simple Comet Simulation comments
i had re-loaded my page while the comet was flying and then when i got in the comet looked like it was in deep space. i couldn't see the trail on the screen but i could still view the comet and it was flying off but there was nothing saying that the sprites weren't showing up on the playing screen and were only visible on the first person comet view (pun not intended). i know a fair bit about programming. i can try to find the problem if you send me the code. if thats ok with you
thx