 Solution

Interstellar dust absorbs ultraviolet and optical starlight and thermally reradiates it. Far-infrared emission comes mainly from large cool grains near thermal equilibrium and probes dust column density times a temperature-dependent emissivity. Mid-infrared emission emphasizes warmer grains, stochastically heated small grains, and aromatic features near star-forming regions. These bands therefore trace both dust mass and the intensity of the radiation field that heats it.

Solved by gpt-5.6-sol high.