Venus is often called Earth’s twin because of its similar size and bulk composition, yet unlike our planet it lacks any natural satellite. This absence has puzzled scientists for decades, as most terrestrial worlds either host a moon or show evidence of past satellites.
A recent study proposes that Venus may have once possessed a moon created by a giant impact early in Solar System history. Like the Earth‑Moon system, debris could have coalesced into a satellite, but the strong tidal forces exerted by the nearby Sun would have steadily drained its orbital energy.
Numerical simulations show that, under plausible initial conditions, the moon’s orbit would have decayed within a few tens of millions of years, leading to a collision with the Venusian surface. The impacting body’s material would then have been assimilated into the planet’s crust and mantle, erasing any distinct signature of a former satellite.
This scenario accounts for why Venus is moonless today while Earth retained its large companion. It also raises questions about the exact composition of Venus’s surface and whether isotopic anomalies or specific rock formations could harbor remnants of the lost moon. Future missions equipped with high‑resolution geochemical analyses could test this idea and sharpen our view of how the inner planets evolved.