Study Says Moon-Sized Impactor Set Venus on 248-Day Retrograde Spin
Updated
Updated · Universe Today · Jun 14
Study Says Moon-Sized Impactor Set Venus on 248-Day Retrograde Spin
1 articles · Updated · Universe Today · Jun 14
Summary
Models presented by ETH Zurich’s Cedric Gillmann indicate a high-angle, high-velocity impactor about one-tenth of Venus’s mass likely altered the planet’s spin within its first 50 million years.
The simulations suggest such a strike could slow a rapidly rotating young Venus into a state consistent with today’s 248-day rotation, and in some tangential cases even flip it into an early retrograde spin.
That impact would also have been geologically extreme, generating magma oceans from roughly 100 kilometers deep to a fully molten mantle and potentially melting about 99% of Venus’s mantle.
Researchers say the heat from such a collision could dissipate efficiently over a few hundred million years, leaving later evolution hard to distinguish from a no-impact case while questions about plate tectonics and interior water remain open.
The work matters beyond Venus’s origin story because rotation strongly shapes climate, cloud formation and habitability, making the planet’s spin history central to understanding whether it could ever have supported milder conditions.
Did a single cosmic punch turn Earth's twin into a hellish, backward-spinning world?
Could the impact that reversed Venus's spin also be what boiled its oceans and erased any chance for life?
How will new missions find the billion-year-old scar from the impact that reshaped Venus forever?
How a Giant Impact Shaped Venus: New Simulations Reveal the Origins of Its Retrograde Spin, Moonless State, and Hostile Climate
Overview
Recent research suggests that Venus’s slow, retrograde rotation and lack of a natural moon can be traced back to a colossal impact event in its early history. In the chaotic early Solar System, giant impacts were common as planets formed and evolved. Scientists now believe that Venus likely experienced such a monumental collision, which fundamentally altered its physical properties. This giant impact could have dramatically changed Venus’s rotation rate and prevented the formation of a moon, setting Venus on a unique evolutionary path that distinguishes it from Earth and other inner planets.