Planetary Geology & Surface Features

A bowl-shaped depression blasted out when an asteroid or comet strikes a solid surface. Craters are the most common landform in the Solar System, and their density is used to date surfaces — the more craters, the older the terrain.

An enormous impact structure, hundreds to thousands of kilometres across, formed by a giant early impact — often multi-ringed and later flooded by lava, as with the lunar maria.

A broad, gently-sloping volcano built by fluid lava flows. On Mars, low gravity and a stationary crust let shield volcanoes grow to enormous size — Olympus Mons is the tallest in the Solar System.

An 'ice volcano' that erupts water, ammonia, or methane instead of molten rock, resurfacing the frozen worlds of the outer Solar System — from Ceres's Ahuna Mons to the plumes of Enceladus.

A broad, dark plain of solidified lava. The lunar maria — the 'seas' — are vast basalt flows that filled ancient impact basins; similar plains cover much of Venus and Mars.

The ancient, heavily-cratered high terrain of a world, older and more rugged than the smooth plains — like the bright lunar highlands or the tessera terrain of Venus.

A deep, steep-sided valley cut by tectonics or water. Mars's Valles Marineris is a canyon system so large it would stretch across the entire United States.

A cliff formed where the crust has broken and one side has risen relative to the other. Mercury is covered in long lobate scarps produced as the planet cooled and shrank.

A chain or massif of mountains, whether uplifted by tectonics, thrown up around an impact basin, or built by volcanism — from Venus's Maxwell Montes to the water-ice mountains of Pluto.

Complex, intensely deformed 'tile' terrain unique to Venus — the planet's oldest and most tectonically tortured surface, ridged and grooved in intersecting directions.

A large circular volcanic-tectonic feature, ringed by fractures, thought to form where hot material rises and pushes up the crust — a signature landform of Venus.

Bright bands of parallel ridges and grooves that cut across the dark, ancient surface of Ganymede — young, tectonically-resurfaced ice.

A field of wind-blown dunes, showing that a world has an atmosphere and mobile sediment — from the basaltic-sand dunes of Mars to the hydrocarbon-sand dunes of Titan.

A giant channel carved by catastrophic floods of water in the distant past, evidence that liquid water once flowed across the surface of Mars.

A fan of sediment deposited where an ancient river entered a standing body of water — a prime target in the search for past life, as at Jezero crater on Mars.

A broad plain or flowing sheet of ice. On Pluto, the nitrogen-ice glaciers of Sputnik Planitia churn and flow; on Mars and the icy moons, water ice shapes the surface.

A jumble of broken, tilted blocks of crust, often where a surface has been disrupted from below — as on Europa, where it may mark places the ice shell interacts with the ocean beneath.

A lake or sea of liquid methane and ethane — found only on Titan, the one other world in the Solar System with stable liquid on its surface.

A steep, isolated mountain on Ceres interpreted as a cryovolcano — a dome built by icy, briny material erupting from within the dwarf planet.

One of the first-recognised tessera regions on Venus — a patch of the planet's oldest, most intensely deformed 'tile' terrain, ridged and grooved by ancient tectonics.

A continent-sized highland region straddling Venus's equator, roughly the size of Africa, cut by deep rifts and dotted with volcanic features.

The largest corona on Venus — a vast circular volcano-tectonic feature ringed by fractures, marking where hot material welled up beneath the crust.

One of the largest impact basins in the Solar System, on Mercury, so violent that its antipode is marked by chaotic 'weird terrain' shaken up by the focused seismic waves.

The strange, dimpled surface of Neptune's moon Triton, resembling the skin of a cantaloupe — a young, resurfaced landscape unlike anywhere else, imaged by Voyager 2.

A region of Europa where the icy crust has broken into a jumble of tilted blocks 'rafts' set in refrozen slush — evidence that the surface interacts with the ocean below.

A young, prominent lunar impact crater with terraced walls and bright rays of ejecta, a classic example of a complex crater.

A great lobate cliff on Mercury, formed as the planet's interior cooled and its crust contracted, thrusting one block of terrain over another.

A 154 km impact crater with a central mountain (Aeolis Mons / Mount Sharp) of layered sediments. The Curiosity rover has climbed it, reading a history of ancient lakes.

One of the largest visible impact basins in the Solar System and the lowest point on Mars, deep enough that the atmospheric pressure at its floor can allow liquid water briefly.

A crater that once held a lake, with a well-preserved river delta at its rim. The Perseverance rover is caching samples here in the search for signs of ancient life.

One of the largest outflow channels on Mars, carved by catastrophic floods of water that burst from the Tharsis region billions of years ago.

The largest known sea of liquid methane and ethane on Titan, near the north pole — the largest body of surface liquid in the Solar System beyond Earth.

The vast lava-filled 'Sea of Showers', one of the largest lunar maria, occupying a giant ancient impact basin on the Moon's near side.

The highest mountains on Venus, rising about 11 km above the mean surface in the northern highlands of Ishtar Terra — higher than Everest above sea level.

A crater on the dwarf planet Ceres famous for its bright deposits — salts left behind by briny water that reached the surface, hinting at a subsurface reservoir.

A vast field of dark, wind-blown dunes wrapping around the north polar ice cap of Mars — one of the largest dune fields on the planet.

The largest lake in Titan's southern hemisphere, a shallow methane-ethane lake whose shoreline changes with the moon's seasons.

An enormous impact basin covering much of the south pole of the asteroid Vesta, with a central peak among the tallest in the Solar System. Its excavation launched the HED meteorites.

The vast nitrogen-ice plain that forms the western lobe of Pluto's bright 'heart'. Its ice slowly churns in convection cells and flows like a glacier, keeping the surface young.

Jagged mountains of water ice rising several kilometres along the edge of Sputnik Planitia on Pluto — water ice is rigid enough at Pluto's temperatures to hold up mountains.

A chain of three vast shield volcanoes on the Tharsis rise, a bulge so large it may have tilted the whole planet. Tharsis dominates the western hemisphere of Mars.

Four parallel fractures across the south pole of Enceladus from which giant plumes of water vapour and ice erupt into space — fed by the moon's subsurface ocean.

A swath of the bright, grooved terrain that covers much of Ganymede — younger ice, tectonically resurfaced into parallel ridges and troughs.

A giant multi-ring impact structure on Callisto — concentric rings of ridges rippling out from a bright central plain across the most heavily-cratered surface in the Solar System.