Mercury Revisited

At first glance, one might mistake this for an image of our familiar lunar neighbor, but it's not. It is, in fact, one of the first close-up images of Mercury taken since Mariner visited the planet over 30 years ago - and it's of a region not seen before. This week, NASA's Messenger spacecraft slipped within 125 miles of Mercury to begin what will be a multi-year exploration of this most unusual planet. The heavy cratering certainly reminds us of the Moon, but looking deeper reveals vast differences between these two solar system bodies. In particular, Mercury is extremely dense - nearly 50% of it's volume is iron - making it denser, even, than the Earth. How did this planet come to be so dense? The Messenger mission has been designed to help scientists answer this intriguing question and a host of others.

If you would like more information on the Messenger mission, including photos and analysis, please visit the mission website.