Mercury Shrank Up to 30% More Than Estimated, Adding About 4.5 Miles of Contraction
Updated
Updated · TIME · Sep 10
Mercury Shrank Up to 30% More Than Estimated, Adding About 4.5 Miles of Contraction
3 articles · Updated · TIME · Sep 10
Summary
A new Geophysical Research Letters study found Mercury contracted up to 30% more than earlier estimates, implying roughly 4.5 additional miles of shrinkage over its 4.5-billion-year history.
Using NASA MESSENGER images, Gaku Nishiyama’s team built new 3D terrain maps from paired 2D views, revealing contraction scars that earlier surveys missed or impact debris had obscured.
The larger shrinkage suggests Mercury’s core may contain less sulfur or silicon, be more metal-rich, or have started hotter, all of which would support faster cooling and stronger contraction.
The findings could reshape estimates for other rocky worlds such as the Moon and Mars, which researchers say may also still be slowly contracting.
BepiColombo, launched in 2018 and due at Mercury in December, is expected to sharpen those measurements with a 20-centimeter laser altimeter before science operations begin in April 2027.