I was actually debating on what to call it before posting. It does look a lot like an underwater explosion to me, and my friends weren't helping at all ("it looks like... a sunrise" "ummm, ok, go away", etc etc) so I used the idea I started with.
i love this, its what i would imagine a really good picture of a blue sun would look like.. i dunno, i like it when things look like they're going to jump off the screen and flow out at you
Yep, as others mentioned, this reminds me of something underwater. It might be the Caedes renderer adding a bit of grain or something... the blue gradient at the top looks like being underwater and looking up at the moonlight.