The fastest winds in the solar system

Here on Earth, the fastest winds on record reached 248 miles per hour (408 km/h) during a tropical cyclone in Australia in 1996. Although that sounds extremely fast, it’s nothing compared to the fastest winds fastest ever recorded in the solar system. Neptune is home to the fastest winds recorded in the solar system, moving at around 1,242 miles per hour (2,000 km/h). If winds of this speed were to occur on Earth, they would move faster than the speed of sound. Interestingly, since the speed of sound depends on air density, the winds on Neptune do not actually exceed the speed of sound on Neptune due to the higher density of Neptune’s atmosphere. Why does Neptune have such fast winds?

Neptune is a mysterious world

Voyager 2 image of Neptune’s atmosphere. Image credit: NASA

Here on Earth, our climate is the direct result of the absorption of solar radiation by our planet. The sun’s heat provides the energy produced during large storms, but given that Neptune is located a staggering 2.7 billion miles (4.3 billion kilometers) from the sun, how does it manage to produce winds of such magnitude? Interestingly, before Voyager 2’s flyby of Neptune, scientists had assumed that Neptune’s atmosphere would be featureless due to lack of solar radiation. Additionally, Uranus’ atmosphere was largely featureless, and it orbits the sun nearly a billion miles (1.5 billion kilometers) closer than Neptune. When Voyager 2 collected data on the temperature of Neptune, astronomers were amazed to find that Neptune’s temperatures are not that different from those of Uranus. Exactly why Neptune is so hot remains a mystery, especially considering the fact that we haven’t returned to Neptune since Voyager 2’s 1989 flyby. Most of what we know about Neptune comes from this overview. Jupiter and Saturn have been visited since Voyager flybys, and the amount of information we’ve gotten on back-to-back missions really shows just how little data you can collect in a single flyby. What we know about Uranus and Neptune now is almost equivalent to what we knew about Jupiter and Saturn 40 years ago. Even in our own solar system, there is still much we don’t know about the outer planets. In the case of Neptune, the reason for its high internal temperatures and fast winds is a mystery. It’s possible that Neptune’s interior allows much greater heat transfer to the surface, causing convection currents that circulate air and temperature. Heat rising from within would power Neptune’s storm systems and generate its supersonic winds. Until we return, we may never know the true reason for Neptune’s storms.

Arline J. Mercier