25 Largest Moons in the Solar System Ranked by Equatorial Diameter

Puck orbits Uranus. Voyager two captured the first close images during its nineteen eighty-six flyby. This dark cratered sphere circles within the inner rings and reflects very little incoming solar radiation across space.

Amalthea circles Jupiter. Galileo spacecraft instruments measured strong thermal heat pouring from its porous interior. Intense Jovian magnetic fields bathe this elongated reddish rock in extreme levels of high-energy trapped particle radiation continuously.

Janus orbits Saturn. Cassini cameras recorded this irregular body swapping orbital positions with sister Epimetheus. Smooth cratered plains cover this low-density rubble pile that measures one hundred seventy-nine kilometers in mean equatorial diameter.

Phoebe circles backward. Cassini captured detailed views showing dark carbonaceous materials blanketing pristine water ice. Scientists classify this distant retrograde body as an ancient planetesimal captured early from the outer Kuiper belt region.

Hyperion tumbles chaotically. Deep sharp-edged craters give this low-density body the unmistakable porous appearance of sponge. Gravitational tugs from nearby giant Titan prevent this spongy world from settling into any predictable rotational rhythm forever.

Mimas mimics fiction. Herschel crater spans one hundred thirty kilometers across a body measuring four hundred. Recent libration measurements suggest this small frozen world might conceal a young liquid ocean beneath its icy crust.

Miranda displays extremes. Verona Rupes drops twenty vertical kilometers down through fractured ice layers and terrain. Intense ancient tidal heating produced dramatic chevron faults and giant oval coronae across this fractured Uranian world today.

Enceladus vents geysers. Cassini flew directly through water vapor plumes erupting from deep fractures called stripes. Hydrothermal vents on the ocean floor supply mineral salts and organic compounds to Saturn's outer ring system continuously.

Tethys reflects brightness. Ithaca Chasma cuts an enormous rift across three quarters of this frigid sphere. Pristine water ice dominates the surface composition of this bright world measuring over one thousand kilometers across completely.

Dione displays fractures. Cassini high-resolution mosaics confirmed bright wispy markings were sheer ice cliffs along faults. Heavy cratering on the trailing hemisphere reveals complex orbital evolution and early bombardment history in Saturnian orbit today.

Ariel appears youthful. Voyager two imaged interconnected fault valleys where smooth cryovolcanic materials filled older scars. Extensional tectonics cracked the brittle water-ice crust while internal warmth drove ancient resurfacing across large global regions historically.

Umbriel remains dark. A bright doughnut deposit of clean carbon dioxide frost highlights Wunda crater floor. Uniformly dark terrain suggests this primordial moon experienced very little internal geological activity after its earliest accretion period ended.

Charon partners Pluto. New Horizons revealed a rust-colored north polar hood created by trapped tholins escaping. Massive canyon systems stretch over one thousand kilometers across the equator of this mutually tidally locked binary companion world.

Proteus orbits Neptune. Voyager two discovered this jagged polygon during its nineteen eighty-nine planetary encounter. Gravity barely failed to pull this heavily battered rock into a smooth hydrostatic equilibrium sphere over cosmic epochs.

Iapetus shows duality. Cassini mapped a mountain ridge twenty kilometers high tracing directly along the equator. Thermal segregation drives dark organic dust to concentrate on the leading hemisphere while bright ice coats the poles constantly.

Oberon circles outermost. William Herschel discovered this distant icy satellite along with sister Titania in seventeen eighty-seven. Dark hydrocarbon deposits coat the floors of prominent impact craters like Hamlet across its heavily battered icy surface today.

Rhea holds ice. Spectroscopic measurements confirm this frigid world consists of seventy-five percent pure water ice throughout. Tenable wispy atmospheres of oxygen and carbon dioxide surround this heavily cratered moon as solar radiation strikes surface frost.

Titania rules Uranus. Belmont Chasma cuts across the southern hemisphere as a massive tectonic graben canyon. Subtle carbon dioxide deposits indicate continuous chemical interactions between solar ultraviolet photons and native surface water ice continuously.

Triton geysers erupt. Voyager two discovered dark nitrogen gas plumes rising eight kilometers into thin atmosphere. Orbital retrograde motion confirms Neptune gravitationally captured this former dwarf planet from the primordial outer Kuiper belt region.

Europa hides oceans. Galileo probe magnetometers detected electrical currents flowing inside a salty global ocean subsurface. Tidal flexure continuously cracks the bright icy shell, producing long reddish bands called lineae across its youthful crust today.

Moon steadies Earth. Apollo missions returned three hundred eighty-two kilograms of basaltic rocks and ancient anorthosite. Gravitational tidal interactions stabilize Earth's axial tilt and maintain predictable seasonal cycles essential for advanced life forms worldwide.

Io erupts violently. Loki Patera and Pele send glowing lava fountains hundreds of kilometers into cold space. Relentless gravitational tides from Jupiter, Europa, and Ganymede continuously melt the interior of this colorful volcanic moon today.

Callisto preserves history. Valhalla basin displays concentric multi-ring impact ripples spanning four thousand kilometers across ancient crust. Lack of internal heat stopped geological resurfacing four billion years ago, preserving an unblemished record of early planetary impacts.

Titan mirrors Earth. Huygens lander touched down among water-ice pebbles rounded by flowing streams of liquid hydrocarbons. Kraken Mare and Ligeia Mare hold vast reservoirs of liquid methane beneath a dense golden photochemical smog haze atmosphere.

Ganymede surpasses Mercury. Juno and Galileo spacecraft confirmed an intrinsic magnetic field powered by liquid iron. Vast grooved terrains crosscut older dark cratered regions, demonstrating complex tectonic upheaval across this giant planetary satellite world.