Scientists at the University of California, Riverside have offered a new explanation for why Venus, often called Earth’s twin, lacks a moon. In a paper published in The Astrophysical Journal, lead author Stephen Krane argues that the planet’s sluggish rotation would have doomed any natural satellite to a slow inward spiral, ending in a collision with the planet.
Slow spin, fast demise
Venus takes about 243 Earth days to complete one rotation—longer than its year around the Sun. By contrast, Earth spins once every 24 hours, more than 200 times faster. Krane’s computer models of hypothetical Venusian moons of various sizes all showed the same outcome: the moons would eventually lose orbital energy and crash into the planet.
The researchers estimate that such a moon‑gobbling event would have occurred within the first billion years of Venus’ 4.5‑billion‑year history. While there is no direct evidence that a moon ever existed, the theory fits with the broader picture of a chaotic early inner solar system, where large rocky bodies frequently collided.
Implications for planetary science
The study adds a new dimension to the long‑standing question of why Earth has a large moon while Venus does not. Previous ideas suggested that Venus never captured a moon or that a moon was destroyed by a massive impact. Krane’s work highlights planetary rotation speed as a key factor in moon retention.
Understanding Venus’ past helps scientists infer the early conditions that shaped Earth’s own history. The planet’s thick, toxic atmosphere and runaway greenhouse effect—temperatures soaring to about 880 °F (471 °C)—make it a valuable laboratory for studying climate extremes.
Future exploration
NASA plans to launch two missions, DAVINCI+ and VERITAS, in the late 2020s to probe Venus’ atmosphere and surface geology. Data from these missions could provide further clues about the planet’s early environment and test hypotheses like the one presented by Krane’s team.
While the idea of a “celestial cannibalism” event remains theoretical, it underscores how planetary dynamics continue to shape the solar system we observe today.
Original reporting: Appleton, WI News Feed (HLL/CB) — read the source article.
