One hundred days of observation of the ‘tsunami’ in the clouds of Venus

March 24 () –

For the first time it has been done a study in time of a gigantic atmospheric wave with the appearance of a ‘tsunami’ that propagates in the deepest clouds of the planet Venus.

It is believed that this discontinuity may be playing a very important role in the acceleration of the Venusian atmosphere, that moves quickly.

Observations were carried out without interruption for more than 100 days. “This observational feat has been possible thanks to the collaboration of amateur astronomers from various countries, who have been the protagonists of the worldwide campaign of observations coordinated with the Japanese mission Akatsuki in 2022”, explains the researcher from the University of Seville and first author. of the study, Javier Peralta.

This article published in Astronomy & Astrophysics has also revealed a truly unexpected fact, since the ultraviolet images taken in June by the UVI camera on board the Japanese mission Akatsuki (which allows us to see the highest clouds of Venus) seem to reflect that the discontinuity was able to propagate for a few hours to about 70 km above the surface of Venus. “It is surprising, because until now the discontinuity appeared ‘trapped’ in the deepest clouds and we had never observed it at such a heightPeralta explains.

The astrophysicist Javier Peralta was responsible for designing in 2022 the strategy for the observations of Venus by the WISPR instrument during the approach/departure maneuvers of the NASA Parker spacecraft during the flybys of Venus. He also contributed to the physical interpretation of the observations, comparing images of thermal emission from the surface of Venus taken by WISPR and Akatsuki’s IR1 camera).

In this sense, the Akatsuki images not only point to the fact that the discontinuity may have spread to the upper clouds of Venus, but also help us understand the reasons for this displacement. In general, the regions where the winds have the same speed as a wave they act as a physical “barrier” for the propagation of that wave.

Because the winds gradually increase with height on Venus and have speeds higher than the discontinuity at the cloud tops, the discontinuity attempts to propagate upward from the deep clouds, but he finds this obstacle in his path and eventually dissipates.

Thus, the experts were surprised when they measured the winds in the high clouds with Akatsuki: they found that they were unusually slow in the first half of 2022, several times slower than the discontinuity itself. And if the winds grow much more slowly with height, it takes longer for the discontinuity to find atmospheric regions as fast as itself, allowing it to spread to higher altitudes.

“Measuring the winds on Venus is critical to trying to explain why Venus’ atmosphere spins 60 times faster than the surface. This atmospheric phenomenon is known as super-rotation. It also occurs on Saturn’s moon Titan and many exoplanets, but after more than half a century or a year of research we still can’t explain it satisfactorily“explains this researcher.