Scientists believe the shrinkage is due to the planet's core slowly cooling.More details at BBC News.
Studies published in the journal Science show the same process also powers the planet's magnetic field, a topic long debated by scientists.
"Cooling of the planet's core not only fuelled the magnetic dynamo, it also led to contraction of the entire planet," said Principal Investigator Sean Solomon of the Carnegie Institution of Washington, US.
"And the data from the flyby indicate that the total contraction is at least one-third greater than we previously thought.
Mercury is shrinking
Posted on Wednesday, July 09 2008 @ 8:50 CEST by Thomas De Maesschalck