Sentence:  No attempts to measure the radio emission of the remaining <WSD>planets</WSD> have been reported , and , because of their distances , small diameters , or low temperatures , the thermal radiation at radio wave lengths reaching the earth from these sources is expected to be of very low intensity . 
Meaning of the word marked with <WSD> tags:  (astronomy) any of the nine large celestial bodies in the solar system that revolve around the sun and shine by reflected light; Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto in order of their proximity to the sun; viewed from the constellation Hercules, all the planets rotate around the sun in a counterclockwise direction