It was a strange illumination, too: cold, sourceless, shifting, ebbing and flowing. I could see the source, roughly ahead of us—an area of what looked like absolute chaos. Light bubbled and roiled in the depths of the crater as though it were a physical fluid. Spreading up into the sky, in an ethereal fan-shape, the air itself seemed to glow with a pearly radiance. This had to be the visual equivalent of the heat-plume the FLIR had shown me, I realized instantly.