Space.com
By Stephanie Waldek
October 6, 2023
Since the 1970s, when NASA’s Mariner 10 mission reached Mercury, scientists have known that the planet is shrinking as its core cools down. But while it’s estimated that thermal contraction started some 3 billion years ago, it hasn’t been clear whether it’s still happening.
But new research conducted by scientists from The Open University in the United Kingdom suggests there’s been fairly recent shrinking-based tectonic activity on Mercury — as recently as 300 million years ago. And that indicates that Mercury might still be shrinking today.