The image: NASA unveiled the first photos from its Mercury Messenger spacecraft on Wednesday, giving astronomers and the public their first detailed, up-close look at our solar system's innermost planet. (See the image below.) Messenger entered Mercury's orbit on March 17, and will spend at least a year photographing and studying the planet. It is the first spacecraft to orbit Mercury, although NASA's Mariner 10 probe made three flybys in 1974 and 1975, only photographing one side of the planet. 
The reaction: The Messenger spacecraft's first photos are "simply lovely," says Phil Plait in Discover. "But there's a terrible beauty in all these pictures" of this "strange little world." Piping hot, dense, battered, largely grey, Mercury is "as unlike Earth as any solid body can be," which will actually help us learn a lot about our own planet. Plenty more high-resolution photos — 75,000 or so — plus seven data-gathering instruments, will tell us a lot about Mercury, says Kenneth Chang in The New York Times. And we'd better enjoy it: We won't get our next "good front-row seat" for the last two unexplored planets, Uranus and Neptune, for a decade or two. In the meantime, enjoy: