Tracing the history of Mars maps is like taking a visual tour of how our thinking about the red planet has changed. Each new telescope and space mission brought about a leap in understanding that is reflected in the maps that followed.

These days our knowledge about Earth's second closest neighbor in the solar system grows by the hour, as the Curiosity and Opportunity rovers explore the Martian surface with five active satellites orbiting above them. And on October 19, the fleet grew by at least one with the successful arrival of the ExoMars Trace Gas Orbiter—although it's not yet clear whether the mission's lander made it safely to the surface.

This month, National Geographic magazine published a beautifully detailed