The fastest wind speeds recorded in the solar system were
measured on Neptune, around the planet's equatorial region.
Large-scale features move from east to west at around 325 m/s
relative to the core of the planet, but smaller features move
faster, at speeds that are up to nearly twice as great. This means
that the jet stream around Neptune's equator approaches
supersonic speeds. The velocity of sound in Neptune's
atmosphere is around 600 m/s.
All the giant planets have strong winds, but it is not clear why
Neptune's are the fastest. They may be influenced by Neptune's
internal source of heat. The second windiest planet is Saturn,
with maximum wind speeds around half the greatest speeds
recorded for Neptune.
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