A cooler core for Earth

Abstract

Geophysics The boundary between the liquid outer core and solid inner core provides a key checkpoint for understanding the temperature structure of Earth. However, determining the melting temperature of iron at a pressure more than 3 million times greater than atmospheric pressure is challenging. Sinmyo et al. measured the melting temperature of iron at these extreme pressures using diamond anvil cells and found it to be 500 to 1000 kelvin lower than some previous estimates. This translates to a lower temperature at the boundary between Earth's outer core and mantle, which suggests that Earth has had a solid lower mantle for at least the last billion years. Earth Planet. Sci. Lett. 510 , 45 (2019).