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
Imiloa Astronomy Center of Hawaii gift shop, and Sky Garden café are open to the public Tuesday through Sunday. An evening "Maunakea Skies" star talk is held in the planetarium on the last Saturday of each month. In the Hawaiian language, ‘Imiloa means "exploring new knowledge." It is located at 600 ‘Imiloa Place in Hilo, just north of Hawaii Route 2000 (Pūʻāinakō Street). In September 2012 the Sagan Planet Walk, until then located only in Ithaca, New York, was extended with a statue representing Alpha Centauri installed at the Imiloa Astronomy Center. This made the Sagan Planet Walk the world's largest exhibition. Imiloa Astronomy Center