New models shed light on how an exotic phase of hydrogen in Earth's core may behave

While Earth's core consists mostly of iron, its density implies that lighter elements are also mixed in. Because hydrogen is abundant in the universe and can mix with iron under certain conditions, scientists suspect it makes up part of the lighter-element composition. Data from earthquakes suggest the inner part of the core also changes with depth, but scientists aren't sure exactly how this occurs. Now, a new study published in the Proceedings of the National Academy of Sciences indicates that hydrogen likely exists in a gradient within the inner and outer core that arises from thermodynamic equilibrium.