blog postsEarth's inner core is doing something weirdAug 20, 2019 11:45 am by National GeographicIllinois in the NewsShare on FacebookTweetEmailImagesNational Geographic (Aug. 19) Earth's inner core of iron floating in molten metal is free to turn independently. Illinois' Xiaodong Song says it’s possible the rate of inner core rotation varies over time. Share on FacebookTweetEmail