According to Matt Braunger, "This picture was taken just before Hoverball Cat took off at supersonic speed. It sounded like a whistle and a scream and the ground caught fire."
I came across another version of the picture where hoverball cat has several clones. This made me wonder if the hoverball cat was really tucking his legs in his thick fur or something else.
Well, after looking around the net for a while, I managed to find the original, un-retouched hoverball cat picture. I can't believe it. I thought the first picture above was real.