JWST has detected \({{\rm{H}}}_{3}^{+}\) and auroral emissions at Neptune—the only giant planet in the Solar System for which they had proved to be elusive up to now. The observations reveal a factor-of-two cooling of Neptune’s upper atmosphere compared with Voyager 2 data, indicative of energy balance processes acting on a shorter timescale than solar forcing.
- Henrik Melin
- Luke Moore
- Katie L. Knowles
