Ground-based telescopes provided unprecedented views, thanks to the positioning of the giant planet in its lengthy orbit around the sun.
NASA scientists have made a groundbreaking discovery, presenting strong evidence of a polar cyclone on Uranus for the first time. Through the examination of radio waves emitted from the ice giant, they were able to detect this phenomenon at the planet’s north pole. This finding confirms a general truth applicable to all planets in our solar system with significant atmospheres: regardless of whether they are primarily composed of rock or gas, their atmospheres display signs of swirling vortices at the poles.
It has been known for some time that Uranus’ south pole possesses a swirling feature. Images taken by NASA’s Voyager 2 of methane cloud tops in that region revealed winds spinning faster at the polar center compared to the rest of the pole. However, Voyager’s infrared measurements did not detect any temperature changes. In contrast, the recent findings, which were published in Geophysical Research Letters, show temperature variations.
By utilizing the massive radio antenna dishes of the Very Large Array in New Mexico, scientists peered beneath the ice giant’s clouds and determined that the circulating air at the north pole appears to be warmer and drier—characteristics indicative of a strong cyclone. These observations, collected in 2015, 2021, and 2022, delved deeper into Uranus’ atmosphere than ever before.
Lead author Alex Akins from NASA’s Jet Propulsion Laboratory in Southern California commented, “These observations provide us with significant insights into the nature of Uranus. It is a much more dynamic world than one might imagine. It is not simply a plain blue gas sphere; there is a multitude of activities occurring beneath its surface.”
Uranus has been captivating scientists lately, courtesy of its orbital position. With its lengthy journey around the sun, spanning 84 years to complete a full orbit, this outer planet has finally realigned its poles towards Earth. This favorable orientation has allowed scientists to obtain a more comprehensive view and explore the depths of Uranus’ polar atmosphere since around 2015.
Ingredients for a cyclone
The cyclone discovered on Uranus bears a resemblance to those observed by NASA’s Cassini spacecraft at Saturn. With this recent breakthrough, scientists have now identified cyclones or anti-cyclones at the poles of every planet in our solar system, except for Mercury, which lacks a substantial atmosphere.
In contrast to hurricanes on Earth, the cyclones on Uranus and Saturn do not form over water, as neither planet is known to possess liquid water. Additionally, these cyclones remain stationary at the poles instead of drifting. Researchers are eagerly monitoring the evolution of this newly discovered cyclone on Uranus in the coming years.
The observation of a warm core in the cyclone raises intriguing questions for scientists. They wonder if this warm core represents the same high-speed circulation observed by Voyager or if there are stacked cyclones within Uranus’ atmosphere. The quest to understand the workings of Uranus’ atmosphere, even in its most basic aspects, fuels excitement among researchers, prompting a desire to unravel more mysteries surrounding this enigmatic planet.
The National Academies’ 2023 Planetary Science and Astrobiology Decadal Survey has placed a high priority on exploring Uranus. Consequently, planetary scientists are diligently expanding their understanding of the mysterious ice giant’s system in preparation for future missions.