- For other uses, see Mercury.
Mercury (Sol I) was a planet, the first planet orbiting Sol in the Sol star system. A class F/class B geomorteus planet, Mercury orbits Sol on an 88-day cycle. A small, rocky body, the surface temperatures on the side facing the sun become quite high due to the close location to the central star. The proximity to Sol is so close as to preclude any semblance of a lifeform-supporting planetary atmosphere. (Last Unicorn RPG module: Planets of the UFP)
Some measurements are derived from real-life scientific studies of the planet Mercury that can be referenced at the Wikipedia page linked in the external link section below.