Whenever I use the magic wand in Photoshauph I get those whitegreyish borders.
If you know how to use your program, use a soften effect and zoom in and replace whitegreyish pixels. Else it looks like something plaster'd above a black background.
Because of this the background and the choppy edge around the meteor makes it look flat and CnP'd. Something that isn't good.
Not saying that you did it, but you should make it blend into the background, instead of making it appear a hovering plane above a flat black surface. Maybe add some small meteors in the background, some "spaceish" or smokeish blurr effects might help to.
In its current state I would recommend you to fix those minior issues before I think this should get approved.
Voting for rejection, you need to fix this up.
Else, it's a nice icon! 4/5 cookies