In the giant system that connects Earth to the sun, one key event happens over and over: solar material streams toward Earth and the giant magnetic bubble around Earth, the magnetosphere helps keep it at bay.
Mars may be experiencing plate tectonics - a phenomenon previously thought to be confined to Earth.
Debate over the origin of large-scale polygons on Mars continues even after several decades of detailed observations - as similarity in geometric patterns on the red planet and Earth have long sparked the imagination.
When scientists discovered two great swaths of radiation encircling Earth in the 1950s, it spawned exaggerated fears about "killer electrons" and space radiation effects.
NASA has published an amazingly detailed map of Mars which was painstakingly rendered using nearly 21,000 images gathered by Odyssey's Thermal Emission Imaging System (THEMIS).