New Theory Suggests Venus May Have Consumed Its Own Moon

Unlike Earth, which has one moon, and Mars, which has two, Venus has no natural satellite. Previous theories posited that Venus might have once had a moon that was destroyed upon collision with a larger celestial body, or that it simply never experienced the kind of impact that formed Earth's Moon. However, the latest study published in The Astrophysical Journal indicates that neither explanation fully accounts for Venus's lack of a moon.

Lead author Stephen Kane explains that gravitational forces, along with the rate of Venus's slow rotation—taking approximately 243 Earth days to complete one spin—would lead to any hypothetical moon spiraling inward and crashing into the planet itself. In contrast, Earth's Moon is drifting away at a rate of about 3.8 cm (1.5 inches) per year due to the planet's rapid rotation.

Kane's team developed computer models to simulate the gravitational interactions of planetary bodies. They initially replicated Earth’s moon formation process to validate their models, then altered variables such as the mass of possible moons around Venus. Most simulations indicated that if Venus had a moon, it would invariably collide with the planet—especially if that moon was larger.

While the research does not conclusively prove Venus had a moon, it suggests that any such moon would have likely been destroyed by these dynamics. The lack of distinct geological evidence on Venus complicates the search for any remnants of a former moon, particularly due to a major resurfacing event about a billion years ago that erased much of its geological history.

The study raises questions about Venus's potential to have ever supported life. A large impact, similar to what could have happened during a moon collision, might have altered the planet’s rotation and climate, potentially enabling conditions suitable for life. However, Kane notes that while having a moon may provide advantages for habitability, it is not a necessity. Future studies on Venus could explore whether geological evidence exists beneath its harsh surface that might hint at this intriguing possibility.