A NASA spacecraft called “Messenger” has finally reached its destination. Messenger launched Aug. 3, 2004, and set a course for Mercury, our solar system’s closest planet to the sun. Messenger finally settled into orbit around Mercury on Thursday, March 17.
Messenger will try to answer many questions about this mysterious planet: Why is Mercury so much denser than Earth, Venus and Mars? Is there ice at Mercury’s polar regions? Why does Mercury have a magnetic field?