Sunrise on Mercury. Artwork of the Sun rising over the surface of the planet Mercury. Mercury is the closest planet to the Sun, orbiting at an average distance of 58 million kilometres, less than half the Earth-Sun distance. The solar wind blasts atoms from its rocky surface, forming a very thin atmosphere that is constantly lost to space. The surface temperature extremes are the greatest in the solar system, ranging (day-night) from 400 to minus 170 degrees Celsius. The Sun rises every 176 Earth days (two Mercury years), but the stars move three times faster across the sky as Mercury takes 59 days to rotate on its axis. Earth with its Moon and Venus are visible (upper right) as the brightest stars in the sky.