Which Planet Has the Strongest Winds?

When Voyager 2 flew past Neptune in 1989, it measured wind speeds of up to 2,100 km/h in the planet atmosphere — the fastest winds in the solar system, faster than the speed of sound on Earth. This is paradoxical: Neptune receives only 1/900th the solar energy of Earth, so its extreme weather must be driven primarily by internal heat. Neptune radiates about 2.6 times more energy than it receives from the Sun, suggesting a significant internal heat source (possibly gravitational contraction or differentiation). The Great Dark Spot, observed by Voyager 2, was an anticyclonic storm roughly Earth-sized. Neptune atmosphere is mostly hydrogen and helium with traces of methane (which gives it its blue colour). Saturn and Jupiter also have powerful winds (up to 1,800 km/h and 620 km/h respectively), but Neptune holds the record despite its tiny energy budget.