A simple model for the statistics of heating of micrometeorites decelerated in the earth's atmosphere without melting predicts that for 10 &mgr;m particles with thermal emissivity near 1, roughly half of those with density 1 g/cc are heated above 550¿C, while half of those with density 3 g/cc are heated above 800¿C. In the study of stratosphere collected interplanetary dust, the model can be helpful in identifying petrographic thermometers of the atmospheric entry process, and in understanding the most recent history of this new class of extraterrestrial material available in the laboratory.