A NASA spacecraft called Messenger swooped across Mercury on January 14. The pioneering craft got as close as 124 miles from the planet's surface. Then Messenger continued a journey that will bring it back to Mercury two more times before settling into a yearlong orbit around the planet in March 2011.
Messenger set off on its mission on August 3, 2004. Since then, it has orbited Earth once and Venus twice. It has already traveled more than 2 billion miles!
The last time a NASA craft visited Mercury was nearly 33 years ago. Mariner 10 flew by the planet three times between 1974 and 1975. It sent back images of less than half of the planet.
Messenger's mission is to study the entire planet. During this flyby, the craft obtained more than 1,200 images. "Only a small fraction of those images has been examined in detail so far," principal investigator Sean C. Solomon told TFK. "But it is already clear that we are seeing new terrain."
Mercury, says Solomon, is a "real oddball." It is the smallest of the eight planets in the solar system, and the closest to the sun. Mercury orbits the sun once every 88 Earth days. It rotates on its axis once every 59 Earth days. Temperatures swing from highs above 840∞F to lows below -350%F.