Giant concentric rings found in Venus's atmosphere

Scientists have discovered giant concentric rings in the atmosphere of Venus, a phenomenon never before observed on the planet. The rings, which are similar to atmospheric gravity waves seen on Earth, were detected by the Japanese Akatsuki spacecraft, which has been orbiting Venus since 2015. The discovery was made by a team led by researchers from the University of Tokyo and was published in the journal Nature Geoscience on January 12, 2021.

The rings, or concentric gravity waves, span thousands of kilometers across Venus's upper atmosphere. They appear as alternating bright and dark bands in ultraviolet images taken by Akatsuki's camera. The waves are thought to be generated by strong winds flowing over mountains on Venus's surface, which then propagate upward into the atmosphere. This finding affects our understanding of Venus's atmospheric dynamics, as such waves can transport energy and momentum between different layers of the atmosphere.

The discovery matters because it provides new insights into the weather and climate of Venus, a planet often called Earth's 'evil twin' due to its similar size but extreme conditions. Understanding these waves could help scientists better understand atmospheric processes on other planets, including Earth. The specific images showing the rings were captured on December 7, 2015, and February 16, 2016, during Akatsuki's early operations. The rings were observed at altitudes between 65 and 70 kilometers, in the cloud layer that gives Venus its yellowish appearance.

Background: Venus has a thick, carbon dioxide-rich atmosphere that rotates much faster than the planet itself, a phenomenon known as superrotation. Previous missions have observed various wave patterns, but these concentric rings are a new addition. The Akatsuki spacecraft, originally launched in 2010, experienced a failure in its main engine and entered orbit around Venus five years later than planned, in 2015.

Next steps: The researchers plan to continue monitoring Venus with Akatsuki to study how these waves evolve over time and to determine their exact role in the planet's atmospheric circulation. They also hope to compare the Venusian waves with similar phenomena on Earth and Mars to better understand planetary atmospheres in general.