Mercury (Mercury) is a planet close to the sun as possible. A small planet And no moon is a satellite The internal structure of Mercury's iron core consists of a large radius of about 1,800 to 1,900 kilometers, surrounded by a layer of silicate. (In the same way that the earth's core is wrapped in the mantle and crust) is only 500 to 600 km thick, some of the core is probably molten.