Neptune Drives 2,000 km/h Winds as 1989 Voyager Data Still Defy Explanation

1 articles · Updated · spacedaily.com · Aug 6

Roughly 2,000 km/h winds on Neptune remain unexplained, leaving the solar system’s fastest known atmospheric speeds as a major open question in planetary science.
1989 Voyager 2 images produced the benchmark estimate by tracking cloud motion, while newer ALMA observations have added direct stratospheric measurements without fully resolving how the winds are powered.
Neptune receives only about one-900th of Earth’s sunlight, so researchers suspect internal heat and rotation drive the atmosphere; the planet emits more than twice the energy it absorbs from the Sun.
Extreme cold may also reduce atmospheric friction, but scientists still lack direct sampling, and a 2013 gravity study suggested the circulation could be confined to a layer only about 1,000 km deep.
That uncertainty persists because Neptune is one of the least explored major planets: one year there lasts 165 Earth years, and no probe has revisited the planet since Voyager 2.