University Of California Riverside

Study: Venus May Have Once Had a Moon That Fell Back Into the Planet

A new study in The Astrophysical Journal argues Venus once had a natural moon that gradually spiraled inward and collided with the planet, explaining why Venus is moonless today. Lead author Stephen Kane, an astrophysicist at UC Riverside, says the moon's demise didn't require a violent impact event, but resulted from the interplay between Venus's gravity and its slow rotation rate.

futurism.com · 2026-09-27

UC Riverside study: Venus may have absorbed its own moon via slow rotation

Researchers at the University of California, Riverside modeled how Venus' extremely slow rotation—243 Earth days per spin—combined with its gravity could have gradually dragged a hypothetical moon inward until it broke apart and was absorbed by the planet. Lead author Steven Kane says this process wouldn't have required a catastrophic collision, contradicting an earlier theory that Venus' moon was destroyed by an impact with another body. The team built a computer simulation of gravitational interactions to test this mechanism.

wired.com · 2026-09-24