<div align="center">i actually made this one because i was board, n i wanted to show how our world is.. see in here: http://reysit0u.deviantart.com/art/Worlds-...iding-122956450</div>
The description was so cliche. But aside from that ; Like said, blending where the planet's meet needs work, doesn't look like they've collided, more like they've been...smudged together. Lighting needs work, particularly on the right hand side planet which is 100% illuminated for no apparent reason, not reflecting the only light source you have there (IE The collision). Don't really understand why you've blurred the edges of the planets either. Background isn't bad, could do with some more star variation but it's okay. The collision itself looks like it could be ok but those weird squiggle lines don't really fit and don't make it look like the planet's are colliding, need removing. Good start.
The effects compared to the planets are either over sharpened or very low quality. Try getting stocks that have the same quality its easier to fix that way. but i do like the idea.