Venus may have once had a moon that was destroyed by tidal forces, according to a study published in the Astrophysical Journal, though the research does not confirm that such a moon ever existed. The study suggests that if a giant impact created a moon around early Venus, tidal interactions could have reversed its orbit, pulling it inward until Venus’s gravity tore it apart.
Astrophysical Journal Study
Professor Stephen Kane
Researchers modeled how a moon formed from debris after a collision might behave. Venus’s rotation speed at the time of the impact would have influenced the moon’s fate. If Venus spun faster than the moon orbited, tidal forces could have initially pushed the moon outward. However, as the planet slowed, the tidal pull would have reversed, causing the moon to spiral inward. In one model, moons twice the mass of Earth’s could be destroyed within 30 million to 1.7 billion years, depending on initial conditions.
University of California, Riverside
Current Venus takes 243 Earth days to rotate once, but simulations suggest its day could have been as short as five to 100 hours shortly after formation. A moon orbiting a Venus with a day longer than 12–15 hours would have been doomed to eventual destruction, according to a study led by Professor Stephen Kane of the University of California, Riverside. The research, which has not yet been peer-reviewed, indicates that even if a moon formed, it likely would not have survived longer than a billion years.
2025 Analysis
The absence of a moon around Venus today could reflect these dynamics. Earlier studies, including a 2025 analysis, suggested Venus experienced large impacts during its formation, but many scenarios would have prevented a stable moon from developing. The idea that solar tides could drive a moon inward dates back to 1973. While the study does not prove Venus ever had a moon, it highlights how tidal forces might have shaped the planet’s evolution.
