A new study published in Geophysical Research Letters suggests that Mercury has undergone significantly greater shrinkage than previously documented by scientists. Researchers estimate the planet contracted between 10% and 30% more than earlier models indicated, resulting in a reduction of approximately 12 miles in diameter since its formation. This finding is particularly noteworthy given Mercury’s current diameter of roughly 3,032 miles.
Scientists had previously underestimated Mercury’s contraction because impact crater debris scattered across the planet’s surface obscured the geological evidence. Gaku Nishiyama, a planetary scientist at the German Aerospace Center Institute of Space Research and study author, notes that understanding the extent of contraction is crucial for studying Mercury’s cooling history and evolutionary development. The research team analyzed data from NASA’s MESSENGER spacecraft, which orbited the planet between 2011 and 2015, comparing maps showing contraction patterns with surface roughness measurements to identify areas where impact debris masked shrinkage signs.
The findings carry implications for understanding Mercury’s internal composition. Greater contraction could indicate a larger metal core and fewer lightweight elements like silicon within that core. These insights into Mercury’s structure may provide valuable clues about planetary formation in the inner solar system. The European Space Agency’s BepiColombo spacecraft, which recently arrived at Mercury, is expected to gather higher-resolution imagery that could refine these measurements further and confirm the study’s estimates.
Originally reported by Livescience →
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