HST & ISO images of the antennae galaxies
Young star clusters in M82, hidden in the optical, visible in the NIR
Compare the IR (ISO) and optical (HST) images -- the most intense IR is not from the two nuclei, but an optically unimpressive region between the nuclei. Clearly, the optical image misses the primary regions of most intense star formation in this interacting galaxy pair.
While the Near-IR NICMOS image of M82 doesn't reveal dust's thermal emission, these wavelenghts do cut through much of the dust's absorption to show otherwise hidden young star clusters.
Image Credit: HST & ISO