Mars Dichotomy (IMAGE) ETH Zurich Caption Mars has two differently shaped hemispheres: the lowlands of the northern hemisphere and the volcanic highlands (yellow to red regions) of the southern hemisphere. A "giant impact" on the southern pole is suspected to be the reason for this. Credit MOLA Science Team Usage Restrictions According to http://www.nasa.gov/about/highlights/HP_Privacy.html#.VMkMJy4XuzI License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.