The first detailed study of the evolution of the discontinuity of the clouds of the planet Venus has been completed, a gigantic atmospheric wave with the appearance of “tsunami” that propagates in the deepest clouds of the planet and that, it is believed, may be playing a very important role in the acceleration of the fast atmosphere of Venus.
The research is the work of a group of scientists from the University of Seville, in collaboration with experts from the University of the Basque Country, in Spain.
The observations were carried out for more than 100 days without interruption.
“This observational feat has been possible thanks to the collaboration of amateur astronomers from various countries, who have been the main protagonists of the global campaign of observations coordinated with the Japanese mission Akatsuki during the year 2022”, explains the researcher from the University of Seville. and co-author of the study, Javier Peralta.
The study has also discovered a truly unexpected event, since the ultraviolet images taken last June by the UVI camera, which allows us to see the highest clouds on Venus and which goes on board the space probe Akatsuki (also known as Venus Climate Orbiter and Planet-C), seem to indicate that the discontinuity was able to propagate for a few hours to about 70 kilometers above the surface of Venus. “This is surprising because until now the discontinuity seemed ‘trapped’ in the deepest clouds and we had never observed it at such a high altitude”, explains Peralta.
Venus seen in ultraviolet light. (Photo: NASA)
The astrophysicist Javier Peralta was in charge of designing the strategy for Venus observations in 2022 by the WISPR instrument on board the Parker space probe during the approach and departure maneuvers of the spacecraft on the occasion of its flybys of Venus. He also participated in the physical interpretation of the observations, comparing WISPR images of the Venusian surface thermal emission and those taken by the Akatsuki IR1 camera.
In this line, the images captured by the Akatsuki not only suggest that the discontinuity could have spread to the upper clouds of Venus, but also help to understand the reasons for this displacement. In general, regions where winds have the same speed as a wave act as a physical “barrier” to the propagation of the wave. Since winds gradually increase with height on Venus and have speeds greater than the cloud top discontinuity, it tries to propagate upward from the deep clouds, but encounters this obstacle on its way and ends up dissipating. Thus, the experts were surprised when, when measuring the high cloud winds with Akatsuki, they observed that they were unusually slow during the first half of 2022, on several occasions slower than the discontinuity itself. And if the winds grow much more slowly with height, the discontinuity takes longer to find atmospheric regions as fast as it, so it can propagate to higher altitudes.
“The measurement of winds on Venus is essential to try to explain why the atmosphere of Venus rotates 60 times faster than the surface. This atmospheric phenomenon is known as super-rotation, it also occurs on Saturn’s moon called Titan and on many exoplanets, but after more than half a century of research we still haven’t explained it satisfactorily”, explains Peralta.
The study is titled “Venus cloud discontinuity in 2022. The first long-term study with uninterrupted observations”. And it has been published in the academic journal Astronomy & Astrophysics. (Source: University of Seville)