Here on Earth, the fastest winds ever recorded reached 248 miles per hour (408 km/h) during a tropical cyclone in Australia in 1996. While that sounds extremely fast, it’s nothing compared to the fastest winds that have ever been recorded in the solar system. Neptune is home to the fastest recorded winds in the solar system, moving at about 1,242 miles per hour (2,000 km/h). If winds of this speed existed on Earth, they would move faster than the speed of sound. Interestingly, since the speed of sound depends on the density of the air, 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 weather is a direct result of our planet’s absorption of solar radiation. Heat from the sun’s sun provides the energy produced in large storms, but considering that Neptune is 4.3 billion kilometers away from the sun, how does it manage to produce winds of this magnitude? Interestingly, before Voyager 2’s flyby of Neptune, scientists had assumed that Neptune’s atmosphere would be featureless due to the lack of solar radiation. In addition, Uranus’ atmosphere was largely featureless, and it orbits the sun almost 1.5 billion kilometers closer than Neptune. When Voyager 2 collected data on Neptune’s temperature, astronomers were surprised to discover that Neptune’s temperatures are not that different from Uranus’s. Exactly why Neptune is so warm is still a mystery, especially considering the fact that we haven’t returned to Neptune since the Voyager 2 flyby in 1989. Most of what we know about Neptune comes from this fly over Both Jupiter and Saturn have been visited since the Voyager flybys, and the amount of information we gained during back-to-back missions really shows how little information you can gather during a single flyby. The amount we know about Uranus and Neptune today is almost equivalent to what we knew about Jupiter and Saturn 40 years ago. Even in our own solar system, there’s still a lot 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 is possible that Neptune’s interior allows much greater heat transfer to the surface, which causes convection currents that circulate air and temperature. Heat rising from the interior would feed Neptune’s storm systems and generate its supersonic winds. Until we return, we may never know the real reason for Neptune’s storms.
Aidan Remple August 1, 2022 in Science