Mercury starts shrinking because of internal cooling
March 18, 2014, 12:10 am TWN
PARIS--Beneath its Sun-scorched exterior, the planet Mercury is cooling, which is causing it to shrink ever so slightly, scientists said Sunday.
Over the last 3.8 billion years, the planet has shrunk by up to 14 kilometers to reach its present diameter of 4,800 km, they said.
Mercury, like Earth, is believed to have a superhot metallic core.
Planetary geologists led by Paul Byrne at the Carnegie Institution for Science in Washington used a tally of these features to get a yardstick for the planet's thermal contraction, the term for shrinkage through heat loss.
They studied nearly 6,000 landforms recorded by NASA's Messenger spacecraft to look for these telltales.
The study appears in the journal Nature Geoscience.