I remind you that you don't have to resize your image because PixelJoint has already a zoom feature built in. You can simply edit your submission and put and 1:1 scale image.
Anyway, the concept is interesting and the technique looks good. The only thing I think you could improve is composition, because the scene looks a bit empty, and antialiasing on the Moon, as "Macaroni and Cheese" said before.
Overall, quite cool
The moon could use some of the recycled colors for AA.