Atmosphere of Mercury Atmosphere of Mercury Mercury has a very tenuous and highly variable atmosphere (surface-bound exosphere) containing hydrogen, helium, oxygen, sodium, calcium, potassium and water vapor, with a combined pressure level of about 10 bar (1 nPa). The exospheric species originate either from the Solar wind or from the planetary crust. Solar light pushes the atmospheric gases away from the Sun, creating a comet-like tail behind the planet. The existence of a Mercurian atmosphere had been contentious before 1974, although by that time a consensus had formed that Mercury, like the Moon, lacked any substantial atmosphere. This conclusion was confirmed in 1974
Radio astronomy service responsibility of the appropriate national administration. The allocation might be primary, secondary, exclusive, and shared. In line to the appropriate ITU Region the frequency bands are allocated (primary or secondary) to the "radio astronomy service" as follows. Radio astronomy service Radio astronomy service (also: "radio astronomy radiocommunication service") is, according to Article 1.58 of the International Telecommunication Union´s (ITU) Radio Regulations (RR), defined as "A radiocommunication service involving the use of radio astronomy". Subject of this radiocommunication service is to receive radio waves transmitte by astronomical or celestical objects. The allocation of radio frequencies is provided according to "Article 5"