This loop of GOES-8 3.9 micron shortwave IR imagery shows the relatively persistent "hot spot" (dark pixels) before, during, and after the eruption of the Popocatepetl volcano near Mexico City at 19:02 UTC on 04 December 1998. A subtle hint of the main ash plume can be seen moving northward, away from the hot spot (the plume itself is somewhat warmer/darker due to solar reflection off the top of the plume; the portion of the ground in the shadow of the plume appears slightly cooler/lighter gray).