This graphic shows a comparison of the internal structures of Earth and Mercury as currently understood based on the latest data from the MESSENGER mission. Mercury’s interior has a larger ratio of metallic core material to silicate rock material than the Earth. Mercury also appears to have a solid layer of iron sulfide that lies at the top of the core. The presence of this solid layer places important constraints on the temperatures within Mercury’s interior and may influence the generation of the planet’s magnetic field. The inset shows a comparison of the relative radial sizes of the Earth and Mercury.
Date acquired: March 21, 2012
Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington