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