Mercury is more shriveled than originally thought

Mercury's surface is covered in craters, ridges and faults. Calculating the amount of crust moved by the ridges and faults shows that the planet has shriveled by seven kilometers over the last four billion years.

Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/NASA

By Science News Staff

March 16, 2014 at 2:00 pm

Guest post by Christopher Crockett

Like a week-old party balloon, Mercury has shrunk over the last 4.6 billion years. And a vastly improved atlas of the scorched planet, courtesy of the MESSENGER spacecraft, shows it’s shriveled more than previously thought. The closest planet to the sun has tightened its belt by about seven kilometers during most of its life, bringing observations in line with computer models that describe Mercury’s inner workings, researchers report March 16 in Nature Geosciences.

Before MESSENGER, only about 45 percent of Mercury’s surface had been imaged. Now astronomers have a nearly complete atlas of the tiny world and can start filling in the details of the planet’s history.