There are a couple of problems:
1) You should be working towards the standard size: 438x1000
2) It doesn't really look like orbital alien activity. If you read
the text in the wiki, it's talking about activity that would seem to me to take place outside of earth's atmosphere, and it's talking about developing weaponry to shoot it down. I think the imagery needs to convey this in some way.
That said, the artwork is alright and I could see something like this being used. I like how you have combined the paintin with a good background photo.
I think there are probably a few "anatomy" issues (if you can call them that) with the UFO, but I'm not enough of an artist to know what to tell you. Perhaps Origin will know better since he seems to be a proper artist and not just a pixel hack like me.