Mercury continues to surprise astrophysicists with its geological evolution. A study recently published in the authoritative scientific journal Geophysical Research Letters reveals that the process of planetary contraction is occurring between 10 and 30 percent faster than previous calculations indicated. The analysis shows that since its birth 4.5 billion years ago, the smallest rocky planet in the solar system has lost nearly 23 kilometers of its original diameter.
The main reason this large-scale compression has remained hidden from science for so long lies in the celestial body's turbulent history. The continuous asteroid bombardment over the eons has scattered huge amounts of rock debris, literally covering and masking geological ridges and folds. Comparing existing maps with new topographic models, the research team found that in the areas with the most pronounced and uneven relief, traces of the contraction have simply been erased under layers of dust and meteorite debris.
To get around this visual problem, scientists turned their attention to the smoother regions of the surface, where tectonic deformations have remained relatively preserved. The results confirm that the planet's cooling process generates significantly more aggressive compression of its rocky crust. According to lead author Dr. Gaku Nishiyama from the Institute of Planetology at the German Aerospace Center (DLR), these data point either to the presence of a much more massive metallic core with a low content of light elements such as silicon, or to a significantly higher initial temperature of the planet during its formation.
The current mathematical model is based on archival data from NASA's Messenger mission, which ended in 2015, whose resolution only allowed the capture of relief structures larger than 5 kilometers. The researchers note that the current values may still be underestimates. The scientific community is eagerly awaiting the upcoming November 2026, when the European-Japanese probe BepiColombo will begin a high-detail scan of Mercury's surface, allowing for the final mapping of planetary compression.