Mercury, As Never Seen Before: MESSENGER visits innermost planet
By Ron Cowen
Mercury’s image problem is fading. On Jan. 14, NASA’s MESSENGER spacecraft flew within 200 kilometers of the solar system’s smallest—and oft-ignored—planet. The craft viewed one crater-pocked hemisphere, half of which had never before been seen close-up. When Mariner 10, the only other craft to visit Mercury, examined the surface 33 years ago, sunlight illuminated a different portion of the planet.
![](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2009/10/7420.jpg?resize=156%2C300&ssl=1)
“Even for the side of Mercury already viewed by Mariner 10, we are seeing the surface with fresh eyes,” says MESSENGER principal investigator Sean Solomon of the Carnegie Institution of Washington (D.C.). “The different lighting conditions, superior image quality, and broader color are showing us new features and providing new information on compositional differences.”