Hey, yeah its just a lil mock-up I did a while back to show an idea. The shock-wave is hard to see on the small screen, I saw a documentary on tv and they were showing explosions but really slowed down frame rate, I saw what looks like a big Jelly like shock-wave around it. And I figured since the At-At explosion was big, it would have added scale.

edit.. heres the shockwave footage, found it...

http://www.youtube.com/watch?v=Aq5TSs-yX0g

I'm also looking forward to see what Ady did to the asteroid bombs. I thought they were EMP charges to disable, but even if they were that, still coulda done with some lightning bolts or something. Just old FX work i guess.