Mercury
Mercury is a planet that orbits the solar system closest to the sun. It is also the smallest inland with a radius of about 2,400 km. The orbital period is 88 days, the rotation period is 58 days, and the density is 5.427 g / cm3. The nucleus occupies more than 70% of the entire aqueous radius and is believed to be composed mainly of iron. The mantle, composed of silicates, occupies the outside. The English name is Mercury. The surface has many craters similar to the moon, and there is a huge cliff formed when the planet shrinks while cooling. There is an atmosphere composed of sodium, potassium, etc., but the strength is very thin in one tenth of the earth. Also, a weak magnetic field was found to exist. Because it is the closest to the sun among the planets, it is strongly influenced by gravitational force, and the orbit moves little by little every year.