Thermal radio radiation has been observed from the moon, Mercury, Venus, Mars, Jupiter, and Saturn. The most important result of the observations is the discovery that the temperature at the surface of Venus, beneath the clouds, is greater than600degK. The thermal radio radiation from the moon comes from beneath the surface and gives information about the temperature distribution and variation which can be interpreted in terms of the physical characteristics of the subsurface material. This also should apply to the planets with thin atmospheres. The thermal radio radiation from Jupiter should give information about the temperature distribution in the extensive absorbing atmosphere, but the intensity of the thermal radiation is confused by the nonthermal radiation of the radiation belts and cannot be accurately specified until more observational data are available.