Mercury is Largely Composed of Iron

The Natural History Museum in London, United Kingdom, claims that iron makes up a considerable portion of mercury. Similar to Earth, it is enclosed in a mantle and crust and has an inner core with an outer core made of liquid metal. Despite Mercury being a considerably smaller planet overall, its inner core is comparable in size to Earth's, according to a 2019 study published in the journal Geophysical Research Letters.

Mercury only has an exosphere, which is the name given to the thin outer layer of Earth's atmosphere; it does not have a full atmosphere. NASA claims that the solar wind and meteoroid impacts that eject atoms from Mercury's surface create the exosphere. Mercury has minimal protection from space debris like asteroids thanks to the exosphere, and the planet is so covered with craters that it resembles Earth's moon. According to the Natural History Museum in London, there aren't any moons around Mercury since it is so close to the sun that the sun's gravity is probably pulling them away.