By using laser-induced fluorescence to visualize liquid drops that are suddenly exposed to supersonic gas streams, we show that the previously available experimental results, which are based on the shadowgraph method, allowed misinterpretations that have lead to inappropriate conceptualizations (and theory) of the physics that govern breakup at high Weber numbers (We>103)—instead of the Rayleigh–Taylor piercing, the dominant mechanism is shear-induced motion with a significant radial component and instabilities on the so-generated, stretched liquid sheet. At low Weber numbers (We<102), the new data reveal the quantitative features of multiwave piercing by Rayleigh–Taylor instabilities. The highly resolved images provide uniquely suitable benchmarks for direct numerical simulations of interfacial instabilities in general and of drop breakup in particular.