Far out and furious
The Windiest Place in the Solar System
Neptune gets almost no sunlight, and yet has the fastest winds anywhere — which nobody fully explains.
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Step 1 of 5
Weather usually runs on sunlight.
Earth's winds are driven by the Sun heating some places more than others. More heating, more weather. It is a reliable rule right up until Neptune.
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Step 2 of 5
Neptune gets almost none.
Noon on Neptune is about as bright as dusk is here It is thirty times further from the Sun than we are. Sunlight spreads out as it travels, so Neptune receives about a thousandth of the light and warmth that Earth does.
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Step 3 of 5
And yet it has the fastest winds we know of.
Streaks in its atmosphere have been clocked at around 2,000 kilometres an hour — several times faster than anything on Earth, and faster than Jupiter, which gets far more sunlight.
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Step 4 of 5
Part of the answer is its own leftover heat.
Neptune gives off more energy than it receives, still slowly releasing warmth from its formation. That internal heat drives weather from below rather than from above.
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Step 5 of 5
And part of it is honestly unresolved.
The cold helps — there is very little to slow the winds down out there. But no explanation yet accounts for the full speed, and one spacecraft has visited, once, in 1989.
Neptune was found by mathematics before it was seen: its pull on Uranus gave away where to point the telescope.
The short version
Neptune has the fastest winds in the solar system despite the least sunlight, driven partly by its own leftover internal heat and partly by something we still cannot fully explain.
Try it yourself
Look up Voyager 2's photographs from 1989. They are still the only close-up pictures anyone has of Neptune.