Study proposes Venus swallowed an early moon due to its slow rotation

Scientists at the University of California, Riverside, have presented a new explanation for why Venus lacks a natural satellite. Using computer simulations of planetary physics, they showed that any moon orbiting Venus would gradually lose altitude and crash into the planet because Venus rotates on its axis once every 243 Earth days, a rate too slow to keep a moon stable. The research, appearing in The Astrophysical Journal, estimates that such a collision would have taken place within the first billion years after the planets formed.

This theory differs from prior hypotheses that Venus never captured a moon or that a moon was shattered by a giant impact. The study also highlights the contrast with Earth, whose rapid 24-hour rotation pushes its moon outward at about 4 cm per year. Future NASA missions, DAVINCI+ and VERITAS, aim to further explore Venus’s atmosphere and geology, potentially shedding more light on its early history.