Recent analysis of the Red Planet’s terrain using NASA’s Mars Reconnaissance Orbiter and Global Surveyor spacecraft observations revealed what appeared to be by far the largest impact crater ever found in the solar system. The image left shows how the Earth might look with a similar sized crater, 5,300 miles wide and 6,600 miles long, embedded in it

NASA’s Viking orbiters observed in the 1970s that the bottom two-thirds of Mars was about two miles higher in altitude than its top third. Planetary scientists have since bandied about two hypotheses to explain the dichotomy: either some odd internal dynamics of Mars generated a thicker planetary crust in the south, or the northern surface was blown away by a mega-meteor impact.

NASA’s Mars Reconnaissance Orbiter and Mars Global Surveyor have provided detailed information about the elevations and gravity of the Red Planet’s northern and southern hemispheres. A new study using this information may solve one of the biggest remaining mysteries in the solar system: Why does Mars have two strikingly different kinds of terrain in its northern and southern hemispheres? The huge crater is creating intense scientific interest.

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