Mercury is the smallest planet in the solar system as well as the closest to the sun. It was named after the Roman messenger god. Its diameter is 3,000, less than half of earth’s. Mercury is very hot during the day, but can get hundreds of degrees below freezing at night. A day on mercury lasts about 59 earth days, and a year on mercury lasts about 88 earth days.
On the inside, mercury consists of a solid iron inner core, and an outer core made of liquid metal. Its crust is rock, covered in craters since the atmosphere is thin, and unlike earth, does not protect it from meteors. Surrounding mercury is a weak magnetic field.
Sky Wonders 