Venus Moon Would Have Been Doomed From The Start, Says New Paper

A new paper claims that Venus would have had no moon due to tidal physics, rather than an exotic catastrophe. The study, by Stephen Kane and colleagues, models the gravitational interactions between Venus, a hypothetical moon, and the Sun over billions of years. The team found that any moon would have spiraled inward and been torn apart by Venus's gravity, likely within the first billion years of the moon's formation. This suggests that Venus's lack of a moon is a natural outcome of tidal forces, not a result of some mysterious event.

The paper uses a computer model to simulate the gravitational tug-of-war between Venus and its hypothetical moon. The model shows that a moon survives only under specific conditions: a fast-spinning early Venus and a moon no heavier than Earth's. The Roche limit, the distance at which a moon is pulled apart by a planet's gravity, is about 2.85 Venus radii, or 17,000 km from the planet's center. Any moon driven inward past this limit would be destroyed, and the debris would rain onto Venus. The study also notes that large moons can stabilize a planet's tilt, making it more habitable.

The paper suggests that NASA’s DAVINCI mission to Venus could find evidence of a destroyed moon, but distinguishing its signature from other factors like volcanic outgassing and atmospheric escape is challenging. If a moon was destroyed and its material fell onto Venus, it could have altered the planet's chemistry and atmosphere. The study predicts that "Venus-like" worlds with slow rotation should also be moonless, offering a testable hypothesis for future research. Earth's Moon is a result of Earth's fast rotation, but if Earth had spun more slowly, the Moon could have been destroyed instead. Venus's slow rotation may have sealed its fate as a moonless body, highlighting the importance of rotational spin in planetary habitability.

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