The temperature of Neptune’s upper atmosphere is very low, but high activity levels like geysers were seen by Voyager 2 in 1989. Surprising because current publications estimate the core temperature at only about 5,400 [Kelvin].
However, based on Noether’s theorem of energy conservation the core must be more than 22,000 [K]. There is no need to search for other heating sources at the core of Neptune and other gas planets.
