Far-infrared brightness temperatures of the planets.

An airborne telescope operating in an altitude range from 45,000 to 50,000 feet together with a low-temperature germanium bolometer and six cooled filters were used in an investigation of the temperatures of the planets. The measurements conducted provide a basis for absolute calibration in the far infrared, confirm the high effective temperature and internal power of Jupiter, and give information on the far-infrared opacities and emissivities of the four bright planets.