The first high-resolution image has been returned from NASA's Messenger Spacecraft, which made its close approach (17,000 miles) flyby yesterday, Jan. 14th, 2008. This flyby is the first of three planned flybys until orbital insertion around Mercury on March 18th, 2011. It is also the first time in almost 33 years that Mercury has been imaged in such great resolution.
Image Courtesy of: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
The above image has a resolution of approximately 6 miles, meaning objects on Mercury's surface as small as six miles can be seen. This image is so interesting to astronomers because this is the first time this side of Mercury has been imaged in high-resolution. Most of the features visible here have never been seen before. The bright spots in the upper right limb of the planet are part of the great Caloris Basin, one of the largest impact basins in the entire solar system. This is the first time the western side of the Caloris Basin has been seen. This of course is exciting news!
Also, Messenger sent back this short time-lapse video of its approach to Mercury.
Video Courtesy of: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
A compilation of pictures sent back by MESSENGER is available in another post here:
Messenger Image Compilation