What Is the Smallest Planet in the Solar System?

What Is the Smallest Planet in the Solar System?

The smallest planet in the solar system, according to the International Astronomical Union's classification, is Mercury, with a radius of approximately 1,516 miles, which is 38 percent the size of Earth. The next smallest is Mars, with a radius of approximately 2,460 miles, or 53 percent the size of Earth.

Pluto, with a mean radius of almost 736 miles, was classified as a planet prior to 2006, when the IAU established a new set of conditions for an object to be considered a planet. This redefinition led Pluto to be reclassified as a dwarf planet. As of 2014, the IAU recognized five dwarf planets in the solar system, including Eris, which is slightly larger than Pluto.