Sixteen years after an experimental polarimeter caught something strange in a single 36-minute window on Venus, an international team led by Gourav Mahapatra (Delft University of Technology) has published the observation and a physical interpretation in The Planetary Science Journal. The signal is remarkable: vast, planet-scale concentric rings encircling much of Venus’s day side, visible only in polarized light — as though the planet were ringing like a bell.
An accidental discovery
The rings were captured on a single clear night in 2010 by ExPo (Extreme Polarimeter), an experimental instrument built by Michiel Rodenhuis (Utrecht Astronomical Institute) and installed on the William Herschel Telescope in the Canary Islands. Unlike an ordinary camera, ExPo isolated linearly polarized light and suppressed everything else, letting atmospheric features hidden in unpolarized data emerge.
Waiting for full darkness on his originally planned targets, Rodenhuis noticed Venus shining in the twilight, consulted colleague Daphne Stam (Leiden Observatory), and pointed the instrument at the planet for 36 minutes. It turned out to be the only session of its kind ever taken. Months later, when the team began analyzing the data, the rings appeared. ExPo was already dismantled by then, its components repurposed for other projects. The observation could not be repeated.
For years the leading suspect was an instrumental artifact, but every check failed to reproduce the pattern from digitization effects, detector smearing, or Earth’s atmosphere.
A signature of Venusian gravity waves?
By 2017, Japan’s Akatsuki probe had confirmed that Venus can support pole-to-pole atmospheric waves — a critical piece of context. Mahapatra used radiative transfer simulations to test whether small-scale density variations induced by atmospheric gravity waves in Venus’s upper atmosphere could reproduce the observed polarization pattern.
Realistic density variations of just 5 to 10 percent turned out to be enough to generate concentric polarization rings closely resembling those recorded in 2010. The simulations further suggest the rings emerge sometime after local Venusian noon, hinting at a link to solar heating as energy propagates through the planet’s dense sulfuric-acid cloud layers.
If confirmed, the rings would provide direct observational evidence that large-scale wave activity produces coherent density structures across enormous regions of Venus’s upper atmosphere — a mechanism potentially central to Venus’s long-standing puzzle of atmospheric superrotation, in which the clouds circle the planet in about four Earth days while Venus itself takes 243 Earth days to rotate on its axis.
Awaiting replication
The team is explicit about the limits: a single unrepeatable observation cannot settle the physics. They have published the result precisely so that modern polarimeters can be pointed at Venus again. If independent observations catch the same rings, the technique would open a new window on atmospheric dynamics — not just on Venus, but on any thick planetary atmosphere, including Earth’s.
© 2026 Homer Dávila Gutiérrez, FRAS — SKYCR.ORG. All rights reserved. Publication: Gourav Mahapatra et al., The Planetary Science Journal (2026). DOI: 10.3847/PSJ/ae7e6f
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 captured vast concentric polarization rings in Venus's atmosphere during a 36-minute observation in 2010. Sixteen years later, Gourav Mahapatra (Delft University of Technology) and colleagues have published the finding in The Planetary Science Journal, arguing the pattern is best explained by density variations of 5–10% induced by atmospheric gravity waves — a signature that could shed light on Venus's mysterious superrotation.){kind=link}