BERKELEY, CALIFORNIA — Earth’s inner core grows 1 millimeter in radius per year, but its east side, beneath Indonesia, is growing faster than its west, beneath Brazil, because it is cooling at a faster rate, causing more iron crystals to form, according to a study in Nature Geoscience.


Because of lower temperatures around the east side, iron crystals form more quickly. However, Earth’s spherical shape is maintained by constant spinning and the force of gravity, which redistribute the extra mass evenly, according to Popular Mechanics.