That's hard to say because new satellites are still being discovered and naturally they are usually the smallest ones.
The smallest planet is MercuryMercury
satellite A1
it is the smallest planet
The moon is a natural satellite of Earth, not a planet.
The Satellite Atlas orbits the planet Saturn.
Oberon is a moon/satellite of the planet Uranus.
The smallest satellite was also NASA's first micro-satellite launched from Alaska on November 20, 2010. The satellite's name was FASTSAT or the USA 220.
Pluto used to be the smallest planet, but it was deemed to not be a planet. The smallest planet now is Mercury within our Solar System
The moon is the smallest out of the Sun,Earth and moon. It should be note, though, that neither the sun nor the moon are planets; the sun is a star and the moon is a natural satellite.
The moon is not classified as a planet at all. It is a natural satellite of Earth.
Mars is the second smallest planet, Mercury is the smallest.
Mercury was listed as the second smallest planet. Since Pluto lost its status as a planet Mercury is now the smallest planet.