Atmospheric physicist Gourav Mahapatra of Delft University in the Netherlands and his colleagues have published findings in The Planetary Science Journal detailing concentric polarization rings discovered in 2010 Venus observations. According to the study, computer simulations indicate these invisible daytime rings may stem from atmospheric gravity waves causing 5 to 10 percent density variations in the upper atmosphere, potentially explaining long-standing mysteries surrounding Venusian atmospheric superrotation.
Unlocking the 2010 Venus Twilight Anomaly
During a chance 36-minute observation on an exceptionally clear evening in 2010, an experimental instrument recorded unexpected phenomena in the atmosphere of Venus. Vast, concentric rings encircled much of the planet’s day side. According to the research team, these formations remained completely invisible except when viewed in polarized light.
The data was gathered using the Extreme Polarimeter (ExPo), an experimental instrument designed by experimental astrophysicist Michiel Rodenhuis during his PhD at the Utrecht Astronomical Institute. Installed on the William Herschel Telescope in the Canary Islands, ExPo suppressed ordinary unpolarized light while recording linearly polarized light. Rodenhuis turned the instrument toward Venus after noticing the planet shining brightly in the twilight while waiting for darkness, collecting data alongside Daphne Stam of Leiden Observatory.
Did you know? Light becomes linearly polarized when it scatters through gas and dust. This optical property allowed the ExPo instrument to reveal subtle atmospheric features that ordinary cameras could not detect.
Testing the Persistent Polarization Signal
Months after the instrument was dismantled and its components repurposed, researchers identified unusual patterns in the Venus dataset. According to Gourav Mahapatra, initial hypotheses suspected instrumental effects, such as digitization processes in the detector or signal smearing, because the rings appeared concentric around the brightest area of the planet.
The signal persisted through rigorous testing. By the time Mahapatra arrived for his PhD in 2017, Daphne Stam had formulated a working hypothesis about the rings. Simultaneously, the Japanese Venus probe Akatsuki observed a pole-to-pole wave in the Venusian atmosphere, confirming that the planet sustains planetary-scale atmospheric waves. Mahapatra tested these ideas using computer simulations.
Simulating Upper Atmosphere Density Variations
Computer modeling revealed that realistic density variations of 5 to 10 percent could produce polarization rings matching the 2010 observations. According to Mahapatra, if confirmed, this provides evidence that large-scale wave activity creates coherent density structures across enormous regions of the upper atmosphere of Venus.
These waves transport energy across the planet. Scientists suspect they maintain Venusian atmospheric superrotation, a phenomenon where hurricane-force winds whip around the entire globe in just four Earth days. This occurs despite Venus taking 243 Earth days to complete a single rotation on its axis. The rings themselves are not the waves, but rather the polarization signature left behind by minor density changes as waves ripple through the thick atmosphere.
Pro Tip: Researchers emphasize that understanding Venusian atmospheric dynamics helps improve fundamental knowledge of Earth’s atmosphere. Despite differences in thickness, temperature, and sulfuric acid clouds, both planets share underlying physical processes.
Next Steps for Detecting Venusian Atmospheric Waves
While the ExPo instrument is long gone, its observations proved that detecting these polarization rings is possible with current technology. According to Mahapatra, new polarimeters deployed on telescopes since 2010—including experimental instruments—can potentially capture these rings.
The research team published their findings in The Planetary Science Journal to encourage the wider scientific community to search for answers and perform new observations. While the exact trigger for the waves remains uncertain, modeling suggests they emerge after local noon in response to solar heating passing through dense cloud layers.
Frequently Asked Questions
What caused the mysterious rings observed on Venus in 2010?
According to computer simulations by Gourav Mahapatra and colleagues, the rings are likely polarization signatures caused by 5 to 10 percent density variations in the upper atmosphere of Venus, driven by atmospheric gravity waves.
What is Venusian atmospheric superrotation?
Atmospheric superrotation is a phenomenon where winds whip around Venus in just four Earth days, despite the planet taking 243 Earth days to complete a single rotation.
Can these polarization rings be seen with standard cameras?
No. According to the study, the vast concentric rings are completely invisible in ordinary light and can only be detected when viewed using polarized light instruments.
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