Here on Earth, the fastest winds ever recorded reached 248 mph (408 km/h) during a tropical cyclone in Australia in 1996. While that seems extremely fast, it’s nothing compared to the -the fastest winds ever 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 there were winds of this speed on Earth, they would travel faster than the speed of sound. Interestingly, since the speed of sound depends on the density of the air, Neptune’s winds 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 absorbing solar radiation. Heat from the Sun supplies the energy produced in large storms, but given that Neptune is a staggering 2.7 billion miles (4.3 billion kilometers) from the Sun, how does it manage to produce winds of such force? Interestingly, prior to Voyager 2’s flyby of Neptune, scientists assumed that Neptune’s atmosphere would be featureless due to the lack of solar radiation. In addition, Uranus’ atmosphere was largely featureless, and it orbited the sun almost a billion miles (1.5 billion kilometers) closer than Neptune. When Voyager 2 collected data on Neptune’s temperature, astronomers were amazed to find that Neptune’s temperatures were not so different from those of Uranus. 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 that flyby. Both Jupiter and Saturn have been visited since the Voyager flybys, and the amount of information we’ve gotten on successive missions really shows how little data you can gather in one flyby. The amount we know about Uranus and Neptune right 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 Neptune’s case, the reason for the high internal temperatures and fast winds is a mystery. It is possible that Neptune’s interior allows much higher heat transfer to the surface, causing convection currents that circulate the air and temperature. Heat rising from the interior will fuel Neptune’s storm systems and generate its supersonic winds. Until we go back, we may never know the true cause of Neptune’s storms.
Aidan Remple August 1, 2022 in Science
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