Biggest To Smallest

Here you can learn about the 30 largest moons (by diameter) in the Solar System! There are over 180 moons that orbit the planets and dwarf planets.  The largest 19 moons in the list below are large enough to have been rounded by their own gravity (this is called being in hydrostatic equilibrium). If these moons were directly orbiting the Sun, that'd be referred to as planets or dwarf planets! In fact the 7 largest moons are larger than any of the known 5 dwarf planets. The largest two moon, Ganymede and Titan, are even larger than the Planet Mercury!

# 1 - Ganymede - 5,268.2 km - Discovered 1610 - Planet Jupiter 

# 2 - Titan - 5,151.0 km - Discovered 1655 - Planet Saturn

# 3 - Callisto - 4,816.8 km - Discovered 1610 - Planet Jupiter 

# 4 -  Io  - 3,636.2 km - Discovered 1610 - Planet Jupiter 

# 5 - The Moon - 3,474.2 km - Discovered Prehistory - Planet Earth

# 6 - Europa - 3,121.4 km - Discovered 1610 - Planet Jupiter 

# 7 - Triton - 2,706.8 km - Discovered 1846 - Planet Neptune

# 8 - Titania - 1,577.8 km - Discovered 1787 - Planet Uranus

# 9 - Rhea - 1,529.0 km - Discovered 1672 - Planet Saturn

# 10 - Oberon - 1,522.8 km - Discovered 1787 - Planet Uranus

# 11 - Iapetus - 1469.0 km - Discovered 1671 - Planet Saturn

# 12 - Charon - 1,207.2 km - Discovered 1978 - Dwarf Planet Pluto

# 13 - Umbriel - 1,169.4 km - Discovered 1851 - Planet Uranus

# 14 - Ariel - 1,157.8 km - Discovered 1851 - Planet Uranus

# 15 - Dione - 1,125.0 km - Discovered 1684 - Planet Saturn

# 16 - Tethys - 1,062.6 km - Discovered 1684 - Planet Saturn

# 17 - Dysnomia - ~700 km - Discovered 2005 - Dwarf Planet Eris

# 18 - Enceladus - 504.6 km - Discovered 1789 - Planet Saturn

# 19 - Miranda - 471.6 km - Discovered 1948 - Planet Uranus

# 20 - Proteus - 420 km - Discovered 1989 - Planet Neptune

# 21 - Mimas - 396.4 km - Discovered 1789 - Planet Saturn

# 22 - Nereid - 340 km - Discovered 1949 - Planet Neptune

# 23 - Hi'iaka - 320 km - Discovered 2005 - Dwarf Planet Haumea

# 24 - Hyperion - 266.0 km - Discovered 1848 - Planet Saturn

# 25 - Phoebe - 213.2 km - Discovered 1899 - Planet Saturn

# 26 - Larissa - 196 km - Discovered 1982 - Planet Neptune

# 27 - Janus - 180 km - Discovered 1966 - Planet Saturn

# 28 - Namaka - 170 km - Discovered 2005 - Dwarf Planet Haumea

# 29 - Amalthea - 167 km - Discovered 1892 - Planet Jupiter 

# 30 - Puck - 160 km - Discovered 1985 - Planet Uranus