Mercury may be shrinking faster than scientists expected - NBC News

A new study suggests the planet Mercury is shrinking 30% faster than previously estimated due to internal cooling. Researchers believe surface debris from impact craters previously obscured evidence of this contraction.
Why it matters
Understanding the geological evolution of Mercury provides critical insights into the formation and cooling processes of terrestrial planets in our solar system.
A new study shows that little, wrinkly Mercury may be shrinking faster than expected, the cosmos’ version of a grape shriveling into a raisin under the sun. Scientists from the German Aerospace Center’s Institute of Space Research reported Thursday that Mercury’s shrinkage may be 30% greater than previously believed — a loss in diameter of as much as 14 miles. That’s significant for a planet barely 3,000 miles across. Mercury’s rough surface, continually reshaped by debris hurled from impact craters, may have hidden the true extent of the loss, according to the researchers whose findings appear in the journal Geophysical Research Letters. The news comes one week after a pair of European and Japanese spacecraft shed its cruising platform and advanced toward Mercury. Known as BepiColombo, the linked craft are expected to enter orbit around Mercury in November before splitting up for a fuller survey.
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