Planet Earth - Inner Core

Although we cannot see Earth's inner core - or be completely sure how it behaves absent first-hand observations - scientists have developed theories about how the core operates.  For example, what happens in the "innermost" part of Earth's inner core?

Harvard University has conducted extensive studies on the subject.  You can read about their findings, at Harvard's website.  This image graphically depicts some of those theories:

Cut-in view of the Earth's interior indicating heterogeneous mantle (upper layer with red and blue variations showing slow and fast seismic wave speed anomalies), outer core (blue region), bulk inner core where the fast axis coincides with the rotation axis (pink region), and innermost inner core where the fast axis does not coincide with the rotation axis (red region).

Click on the image for a better view.