Scientists may have uncovered a possible reason why Venus, often called Earth's twin, doesn't have a moon—suggesting the planet may have once had one that was destroyed. Venus and Earth are similar in size, mass, and composition, yet Venus has no natural satellite, unlike Earth. The only other planets in our solar system without moons are Mercury and Venus. A team of researchers, led by Stephen R. Kane from the University of California, Riverside, used computer simulations to explore what might have happened to a hypothetical moon orbiting Venus. Their findings suggest that any moon would likely spiral inward due to Venus's strong gravity and be torn apart, rather than drifting outward as Earth's moon does. This outcome depends on factors such as Venus's rotation speed and the moon's mass. For a moon to have survived, Venus would have needed to rotate much faster—its day would have had to be shorter than about 12 hours—and the moon's mass would have had to be no more than roughly that of Earth's moon. However, these conditions don't match what scientists currently understand about early Venus, suggesting that such a moon may have never existed or may have been destroyed. Finding direct evidence of a destroyed moon is challenging, as any remnants from billions of years ago would likely have left little trace. However, scientists might find indirect clues in the chemical composition of Venus's surface or atmosphere. Future missions, like NASA's DAVINCI probe, will analyze the planet's atmosphere for potential signs of past moons. The study's findings also suggest that slowly rotating planets similar to Venus orbiting other stars are unlikely to have large moons. This prediction could be tested as astronomers search for moons around exoplanets. The research is currently available as a pre-peer-reviewed paper on arXiv.