The planet with the strongest winds in the solar system, often called the windiest planet, is:

Neptune has the fastest winds measured on any planet in the solar system. Winds in its atmosphere can reach about 2,000 km per hour, which is faster than the speed of sound on Earth.

Why the winds are so strong:

It is surprising that the planet farthest from the Sun, which receives very little solar energy, has the strongest winds.

Scientists think that Neptune's internal heat drives its weather. Neptune gives off more than twice as much energy as it receives from the Sun.

Because its atmosphere is very cold and has little friction, once winds start they can keep blowing at very high speeds.

Storms on Neptune:

• In 1989, Voyager 2 observed the Great Dark Spot, a huge storm about the size of the Earth.
• By 1994, when the Hubble Space Telescope observed Neptune, the Great Dark Spot had disappeared, but new dark spots have appeared since.

About Neptune:

It is the eighth and outermost planet of the solar system, about 4.5 billion km from the Sun (30 AU).

It is an ice giant, with an atmosphere of hydrogen, helium and methane. Methane gives it a deep blue colour.

It takes about 165 Earth years to complete one revolution around the Sun.

Discovery:

• Neptune was the first planet whose existence was predicted by mathematics before it was seen.
• Urbain Le Verrier of France and John Couch Adams of England calculated its position from irregularities in the orbit of Uranus.
• Johann Galle observed it on 23 September 1846 at the Berlin Observatory.

Exploration:

Voyager 2 is the only spacecraft to have visited Neptune, flying past it in August 1989.

Why not the other options?

• ✗Mars has dust storms, but its winds are much weaker.
• ✗Venus has fast upper-atmosphere winds, but they are slower than Neptune's.
• ✗Earth's strongest winds occur in tornadoes and cyclones but are far weaker than Neptune's.