Intermittent bursts of light penetrate the thick veil of clouds enshrouding Venus. Earlier investigations have hinted at the possibility that these gleams might be manifestations of lightning within the turbulent atmosphere of this fiery world. However, a recent study has unveiled a surprising twist: the majority of these flashes may not be lightning at all but instead brief, radiant events originating from meteors.
As we look ahead to upcoming missions set for Venus, scientists are determined to demystify these luminous events (Source: SN: 6/2/21). If these flashes do indeed stem from lightning, the resulting electrical discharges could pose substantial risks to future probes destined to descend through the Venusian atmosphere or float among the planet's clouds for extended periods, warns Claire Blaske, a planetary scientist now affiliated with Stanford University. Conversely, the incineration of small meteors within the atmosphere would pose negligible hazards.
Previous missions to Venus have often detected electromagnetic interference resembling the static frequently encountered on AM radio, a clear indicator of lightning activity during terrestrial thunderstorms, as elucidated by Blaske. Additionally, orbiters and Earth-based telescopes have recorded brief, dazzling flashes within Venus' atmosphere.
However, an intriguing puzzle persists: the static and the optical flashes have never been observed simultaneously, as highlighted by Blaske. Paul Byrne, a planetary scientist at Washington University in St. Louis, who was not involved in the study, comments, "It remains unclear whether Venus harbors the potential for lightning," underscoring the limited knowledge concerning the intricate dynamics of its atmosphere.
During her tenure at Arizona State University in Tempe, Blaske and her colleagues contemplated the intriguing possibility that meteors might be impersonating lightning on Venus. Two independent surveys were conducted to quantify these luminous events: one utilizing a telescope situated on Arizona's Mount Bigelow and the other deploying instruments aboard Japan's Akatsuki orbiter (Source: SN: 12/8/15).
According to the data gathered, it is estimated that there are likely between 10,000 to 100,000 such flashes occurring annually, as reported in the researchers' findings published in the September edition of the Journal of Geophysical Research: Planets.
While this initially may appear to be an excessive number of flashes for meteors to account for, it is crucial to consider that Venus, though slightly smaller than Earth, witnesses meteors that are significantly more luminous, rendering them considerably more conspicuous. This heightened visibility is attributed to the fact that these celestial bodies traverse Venus' atmosphere at an average velocity of about 25 kilometers per second, compared to Earth's meteoroids, which enter its atmosphere at 20.3 kilometers per second. This difference can be partly attributed to Venus' swifter orbit around the sun in comparison to Earth's.
Considering these factors and others, Blaske and her colleagues suggest that meteors could indeed be numerous enough to explain the majority, if not all, of the luminous events within Venus' atmosphere.
Byrne applauds the team's analysis, deeming it persuasive and a significant step toward providing a plausible explanation for these perplexing flashes. Nonetheless, the enigma surrounding Venus' lightning-like phenomena remains far from resolved. Lingering questions include whether Venus might experience various forms of electrical discharges, including lightning or other anomalous occurrences, within its carbon dioxide-rich atmosphere, which may not manifest as visible flashes but could still pose potential risks to approaching probes.