The closest planet to our sun is shrinking. Here’s what that means

Key Points:

• New research suggests Mercury has shrunk 10% to 30% more than previously estimated, indicating a radius reduction of about 7.2 miles (11.6 kilometers), compared to earlier estimates of up to 4.3 miles (7 kilometers).
• Mercury's surface wrinkles, or shortening structures, are partially obscured by impact debris from asteroids and comets, complicating assessments of the planet's contraction over time.
• Understanding Mercury's shrinkage can provide insights into its interior composition, core size, tectonic history, and magnetic field generation, as the planet has a large metallic core relative to its size.
• The upcoming BepiColombo mission, arriving at Mercury with two orbiters, will offer unprecedented global topographic data, especially of the southern hemisphere, to better measure Mercury's contraction and surface features.
• Despite compelling new findings, some scientists caution that significant shrinkage should cause visible large-scale surface buckling, suggesting further research and possibly surface exploration are needed to fully understand Mercury's geological evolution.