Mercury Shrunk Far More Than Thought

Updated: 2026.09.15 1H ago 1 sources
Combining MESSENGER laser altimetry with global image-based terrain models reveals previously obscured crustal wrinkles, leading researchers to estimate Mercury contracted 10–30% more than earlier figures—possibly up to a 14.5-mile diameter reduction—implying a larger, purer metal core or hotter early history. Impact debris had hidden many shortening structures, and the BepiColombo spacecraft will soon provide independent data to confirm or refine these numbers. — This changes quantitative models of planetary cooling and interior composition, affecting comparative planetology and how we interpret exoplanet interiors from limited observables.

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Mercury Has Gotten Smaller Than We Thought
Jake Currie 2026.09.15 100% relevant
MESSENGER laser-altimeter data combined with image-based digital terrain models and the new study by Gaku Nishiyama (German Aerospace Center) that reports 10–30% higher contraction and cites up to 14.5 miles of shrinkage; BepiColombo's imminent data arrival is noted as a validation opportunity.
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