Things I learned: Good detailed renders that are big lose their quality when transformed to smaller size so what I did is enlarge a 640 by 480 pic I shot to a wallpaper size (wherein the render fits). It is recognizable enough as a bg plus its blurry attribute helps emphasize the render. I also recycled the planet from my old XCF work and played with layer modes. I found out that white color and difference mode works like color invert. I added a red glow on his eye just for cool looks. I also darkened the bg... It looks like night time right?
Seeing that the Gimp 2.8 stable version is available now in the Gimp.org site makes me feel excited. I will be looking forward to new tutorials from fellow Gimpers. After a long wait, the time has come comrades. Great work developers, contributors, translators, sponsors and moral supporters!
I also just experimented with color curves for the bg and so intentionally made the right side look strong and sharp but yeah it's so bright for the eyes. The left side is colored while the right side is inverted and reddish but the dark left was left out and the right stand out than the other. 
