A cosmic origin of Venus’ lower haze
(2026) Nature Astronomy — (2026)
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- Authors
Karyu, Hiroki 
Kuroda, Takeshi Määttänen, Anni Mahieux, Arnaud
- Abstract
- Unlike on Earth, where liquid droplets persist from the surface to the cloud tops1, droplets on Venus evaporate in the hot lower atmosphere and never reach the surface2. Yet, entry probes have consistently revealed a layer containing involatile particles3–5—the lower haze—between Venus’ surface and the main cloud deck. However, the origin of the lower haze layer has remained unknown since its discovery five decades ago. There has never been an attempt to reproduce the lower haze layer or investigate its origin in cloud modeling of Venus; instead, it has typically been treated as a given boundary condition6–9. Here we incorporate a self-consistent particle formation framework into a Venus cloud microphysics model and show, for the first time, that the continuous influx of cosmic dust is sufficient to sustain this lower haze layer with the particle size distribution observed by the entry probes. These haze particles of cosmic origin act as efficient condensation nuclei, promoting cloud formation in the main cloud deck even far from their initial source.Beyond this, these particles also provide a plausible source for the planet’s long-unidentified ultraviolet absorber. Collectively, our findings establish cosmic dust as an essential component of Venus’ climate. These insights are also crucial for understanding the climates of planets with thick atmospheres, such as gas giants and exoplanets, where accumulating cosmic dust can similarly affect the cloud structure and composition.
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Citations
Karyu, H., Kuroda, T., Määttänen, A., Mahieux, A., Viscardy, S., Terada, N., Robert, S., Vandaele, A., & Crucifix, M. (2026). A cosmic origin of Venus’ lower haze. Nature Astronomy. Published. https://doi.org/10.1038/s41550-026-02843-4 (Original work published 2026)