Story perspectives

Study Finds Mercury Shrunk Up to 14.5 Miles

By Drooid · Sep 11, 2026, 6:54 AM UTC · How we work

Summary

Story summary

DLR scientist Gaku Nishiyama’s team found Mercury’s radius shrank up to 14.5 miles, 10-30% more than previously thought.
Researchers combined MESSENGER geological maps with new global surface-roughness data to count hidden contraction ridges.
Accounting for hidden features, the study estimates Mercury’s radial contraction at 4.3-7.2 miles (6.9-11.6 km).
More shrinkage suggests Mercury’s metal core is larger and contains fewer light elements like silicon.

History

Historical Context

On 29 March 1974 NASA’s Mariner 10 performed the first Mercury flyby, using Venus gravity assists to obtain over 2,800 images and map 45 % of the surface, revealing a magnetic field and a large iron-rich core. Those findings shaped later missions—NASA’s MESSENGER (2004-2015) and the ESA-JAXA BepiColombo probe slated for 2026. University of Tokyo scientist Gaku Nishiyama now refines core estimates with MESSENGER data.

1 of 2

Story summary

DLR scientist Gaku Nishiyama’s team found Mercury’s radius shrank up to 14.5 miles, 10-30% more than previously thought.
Researchers combined MESSENGER geological maps with new global surface-roughness data to count hidden contraction ridges.
Accounting for hidden features, the study estimates Mercury’s radial contraction at 4.3-7.2 miles (6.9-11.6 km).
More shrinkage suggests Mercury’s metal core is larger and contains fewer light elements like silicon.

1 / 2