The MESSENGER spacecraft took this photo of Mercury on October 10, 2009, from a distance of almost 2 million miles.
Just days earlier, MESSENGER flew over the surface of the innermost planet at an altitude of only 140 miles.
With no atmosphere to disperse heat, the day side of Mercury can reach nearly 800º F while the night side’s temperatures plummet to -300º. Now the smallest official planet in the solar system, Mercury is 38% the size of Earth…about the difference between a baseball and a golf ball.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.