Recently NASA has revealed the smallest planet outside solar system.
This Planet is slightly larger than the Moon and orbits its Sun like host star every 13 days.
About the Smallest Planet outside solar system
NASA’s Kepler space telescope detected the smallest planet yet found around a star similar to the Sun in a new planetary system. The planets are located in a system called Kepler-37, about 210 light-years from Earth in the constellation Lyra.
The smallest planet, Kepler-37b, is slightly larger than our Moon, measuring about one-third the size of Earth. It is smaller than Mercury, which made its detection a challenge.However, while the star in Kepler-37 may be similar to our Sun, the system appears quite unlike the solar system in which we live.
Astronomers think Kepler-37b does not have an atmosphere and cannot support life as we know it. The tiny planet almost certainly is rocky in composition.
Kepler-37c, the closer neighbouring planet, is slightly smaller than Venus, measuring almost three-quarters the size of Earth. Kepler-37d, the farther planet, is twice the size of Earth.