Only a little larger than Earth's moon, Mercury is the smallest of the eight planets in the Solar System and is also the closest to the Sun. With a surface area of 28,879,000 square miles, Mercury's circumference at its equator is 9,525.1 miles.
In contrast, the Solar System's largest planet, Jupiter, has a surface area of 23,713,907,537 square miles and an equatorial circumference of 272,945.9 miles. For many years, Pluto was considered the system's smallest planet, but it was demoted to dwarf planet status in 2006. The planets in order of size from smallest to largest are Mercury, Mars, Venus, Earth, Neptune, Uranus, Saturn and Jupiter.