One of the largest features on Mars is its hemispheric dichotomy: the difference in crater density, elevation (~4 km), and crustal thickness (~30 km) between the Northern Lowlands and the Southern Highlands. Recent impact cratering simulations show that the ~10,000 km diameter Lowlands can be formed by a single large impact. This impact size was common at the end of planetary accretion and falls in the planetary-scale impact size regime, in which the curvature and radial gravity of the planet are important. Dr. Marinova will discuss the implications of her research into the puzzling Martian hemispheric dichotomy.