Mercury has shrunk by 11 kilometres since its birth and continues to contract, study finds

Mercury has shrunk by 11 kilometres since its birth and continues to contract, study finds (Image: Canva)

Mercury, the smallest planet in our solar system, continues shrinking slowly. Scientists now reveal clearer measurements of the planet’s contraction.

Planet’s Shrinking Radius Measured Accurately

New research shows Mercury’s radius has decreased by 2.7 to 5.6 kilometres. Earlier estimates ranged from one to seven kilometres, causing uncertainty. The interior of the planet has cooled down, causing its rocky crust to adapt. Gigantic thrust faults developed, producing cliff-like scarps on the surface. Researchers have previously estimated shrinkage from fault heights and lengths with variable results.

Fresh Method Reveals Precise Contraction

Researchers Stephan R. Loveless and Christian Klimczak used a new approach. They measured the largest faults in each dataset to estimate shrinkage. Three datasets were tested, ranging from 100 to nearly 6,000 faults. All datasets suggested two to 3.5 kilometres of shrinkage from faulting alone. Adding other cooling processes brings total contraction up to 5.6 kilometres.

Implications Beyond Mercury

Mercury shrinks because its iron-rich core loses heat faster than Earth’s. As the core contracts, the crust adjusts to a smaller volume beneath. The total diameter has reduced by nearly 11 kilometres since formation. This method could also study tectonics on rocky worlds like Mars. Researchers hope it offers more insights into planetary evolution over time.