Figure 1 shows an example of a collision-induced absorption spectra of H 2 -He complexes at a variety of temperatures. The spectra were computed from the fundamental theory, using quantum chemical methods, and were shown to be in close agreement with laboratory measurements at temperatures, where such measurements exist (for temperatures around 300 K and lower). The intensity scale of the figure is highly compressed. At the lowest temperature (300 K), a series of six striking maxima is seen, with deep minima between them. The broad maxima roughly coincide with the H 2 vibrational bands. With increasing temperature, the minima become less striking and disappear at the highest temperature (curve at the top, for the temperature of 9000 K).