Early Tuesday morning, NASA's Messenger spacecraft sent home the first image of Mercury ever taken from orbit around the planet.

The picture, taken at 5:20 a.m. EDT on March 29, shows a wide swath of Mercury's southern hemisphere. The bright crater at the top of the image is called Debussy, and a smaller crater called Matabei lies to Debussy's west. The shadowed, pockmarked region south of the bright craters includes Mercury's south pole and slice of terrain that had never been seen up close before.

When Messenger became the first spacecraft ever to orbit Mercury on March 17, it had already mapped 98 percent of the planet's surface. But those earlier images were snapped as the spacecraft zipped past to adjust its trajectory. Now that Messenger is in orbit, it will have the chance to explore every crater and crevice of the solar system's smallest planet in detail.

The good stuff is still on its way. The orbiter took 363 more images of the planet's surface in the six hours after this first image was captured, and is in the process of downlinking them to Earth. These initial images are part of the commissioning phase, to make sure all the instruments are working. The true-science phase of the mission begins April 4. It calls for 75,000 more images before the orbiter's science goals are complete.

NASA will hold a teleconference at 2 p.m. EDT Wednesday to discuss this first shot of the innermost planet and release more photos. Stay tuned!

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

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