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
Elongation (astronomy) a moon of another planet from its central planet, for instance the angular distance of Io from Jupiter. Here we can also talk about "greatest eastern elongation" and "greatest western elongation". In the case of the moons of Uranus, one often talks about "greatest northern elongation" and "greatest southern elongation" instead, due to the very high inclination of Uranus' axis of rotation.. Elongation (astronomy) In astronomy, a planet's elongation is the angular separation between the Sun and the planet, with Earth as the reference point. The greatest elongation of a given inferior planet occurs when this planet’s position, in its