Atmosphere of Uranus at the solstice of 1986, when "Voyager 2" passed by the planet, they were concentrated near the sunlit pole, making it dark in ultraviolet light. The outermost layer of the Uranian atmosphere, extending for thousands of kilometres, is the thermosphere/exosphere, which has a uniform temperature of around 800 to 850 K. This is much higher than, for instance, the 420 K observed in the thermosphere of Saturn. The heat sources necessary to sustain such high temperatures are not understood, since neither solar FUV/EUV radiation nor auroral activity can provide the necessary energy. The weak cooling efficiency due to the depletion
Atmosphere of Venus Earth, the upper atmosphere has been proposed as a location for both exploration and colonization. On January 29, 2013, ESA scientists reported that the ionosphere of the planet Venus streams outwards in a manner similar to "the ion tail seen streaming from a comet under similar conditions." Mikhail Lomonosov was the first person to hypothesize the existence of an atmosphere on Venus based on his observation of the transit of Venus of 1761 in a small observatory near his house in Saint Petersburg, Russia. The atmosphere of Venus is composed of 96.5% carbon dioxide, 3.5% nitrogen, and traces of other