There are currently 173 known natural satellites (or moons) in the Solar System, excluding the moons of dwarf planets. The largest natural satellite in the Solar System is Jupiter's moon, Ganymede. Ganymede and Saturn's largest moon, Titan, are bigger than the planet Mercury. Earth's Moon is the fifth largest moon in the Solar System after Ganymede and Triton (listed above), Callisto and Io. Titan often appears to be on because of its dense atmosphere which makes it appear to be just gas, ad the surface of the moon is not visible. Only 7 of the 173 known moons in the colar system are more than 2,000 kilometers in diameter.

List of natural satellites in the Solar System by sizeEdit

This is a list of the moons which have a radius of 550 kilomters or more in the Solar System of planets and dwarf planets. 

Satellite of Earth Satellite of Jupiter
Satellite of Saturn Satellite of Uranus
Satellite of Neptune Satellite of Pluto
Name Radius (km) Atlernative name Discovery year Discovered by
Ganymede 2,634.1 Jupiter III 1610 Galileo Galilei
Titan 2,575.5 Saturn VI 1655 Christiaan Huygens
Callisto 2,408.4 Jupiter IV 1610 Galileo Galilei
Io 1,818.1 Jupiter I 1610 Galileo Galilei
Moon 1,737.1 Earth I ---- ----
Europa 1,560.7 Jupiter II 1610 Galileo Galilei
Triton 1,353.4 Neptune I 1846 William Lassell
Titania 788.9 Uranus III 1787 William Herschel
Rhea 764.5 Saturn V 1672 Giovanni D. Cassini
Oberon 761.4 Uranus IV 1787 William Herschel
Iapetus 734.5 Saturn VIII 1671 Giovanni D. Cassini
Charon 603.6 Pluto I 1978 James W. Christy
Umbriel 584.7 Uranus II 1851 William Lassell
Ariel 578.9 Uranus I 1851 William Lassell
Dione 562.5 Saturn IV 1684 Giovanni D. Cassini