By Hanneke Weitering, All About Space
The pictures in space are of landforms on Earth that were taken by the International Space Station crew.
Some of the universe’s most breathtaking geological delights have been brought home by space exploration. Toppling mountains that outgrow Everest! Canyons big enough to swallow our Grand Canyon whole! Spacecraft have returned mind-blowing images of landforms that defy our sense of planetary geography. These alien vistas are stories written on the ground in volcanic fury, dying rivers, impact violence and forces we’re only just starting to learn how to read.
Since its first chance encounter with an asteroid in 1968, robotic explorers have pinballed between the planets and moons in our solar system, beaming home images that have transformed alien landscapes into familiar places. A few planets have characteristics that make the Earth’s most impressive features look downright modest in comparison. Others have geological oddities no scientist forecast. Every discovery changes the way we think planets are made, change and evolve over billions of years.
This article discusses nine of the most impressive planetary landforms ever captured by spacecraft. These aren’t simply nice images—they’re portals into the chaotic hallways that have sculpted worlds throughout our solar system. From Mars to Saturn’s moons and from Mercury to Neptune’s largest moon, these geologic wonders are an illustration that our cosmic backyard is more grand and intriguing than early astronomers could have ever dreamed.
Olympus Mons, the Solar System’s Largest Mountain
Sticking up a towering 13.6 miles (22 kilometers) above the Martian surface, Olympus Mons is the tallest volcano in our solar system. This shield volcano covers an expanse about as large as that of Arizona, and is therefore not simply tall but monumentally broad. The caldera at its top—a depression created by caved-in magma chambers—is 50 miles across and dotted with overlapping craters.
The geological giant was first spotted in 1971 by NASA’s Mariner 9 spacecraft, though early astronomers had seen what they believed to be a bright patch in the region through their telescopes, and some named it “Nix Olympica” or “Snows of Olympus.” Additional images taken by Viking orbiters exposed the scale of the mountain.
What is making Olympus Mons so large? On Mars, there is no plate tectonics: the volcanic “hotspots” are fixed for millions of years. On Earth, tectonic plates ride over hotspots, forming volcanic island chains like Hawaii. On Mars, lava just kept emplacing in the same spot, growing and growing. It could grow taller without collapsing under its own weight, thanks to lower gravity on the planet.
The slopes of the volcano are exceptionally low: you could make your way from base to summit with an incline that averages only 5 degrees. The edges, though, are a different matter. All sides of the volcano are surrounded by cliffs up to 5 miles high, likely produced by catastrophic landslides. These escarpment walls define a sharp break between the volcano and the surrounding plains.
It is thought that Olympus Mons was still active quite recently in geological terms, possibly as little as 2 million years ago. Lava flows at different levels are of varying age, and indicate that eruptions of the volcano were separated by periods of volcanic inactivity throughout Martian history.
Valles Marineris: A Canyon System Bigger Than the Grand Canyon
The largest canyon system in the Solar System, Valles Marineris extends for 2,500 miles along the Martian equator. At its nadir, this chasm system—a fractured network of canyons—lies 4 miles beneath the surrounding plateaus, or some four times deeper than the Grand Canyon. If Valles Marineris were placed on Earth, it would stretch the whole distance from one coast of the United States to the other.
The Mariner 9 orbiter first found this outstanding feature in 1971, which is now named for the historic mission. Whereas the Grand Canyon was carved by a river, Valles Marineris has an entirely different origin. Scientists suspect it was born when the Tharsis volcanoes billions of years ago swelled up, breaking apart, collapsing and wrinkling like stretched plastic wrap.
The canyon system is made up of many different segments and features. The western canyons are marked with signs of old volcanic activity. The middle panels show gargantuan landslides that became debris flows flowing for hundreds of miles. The east canyons contain stratigraphy which indicates that water may have ponded there in the past, potentially indicating ephemeral lakes.
Recent images from the Mars Reconnaissance Orbiter have shown some interesting aspects of the canyon walls. Layered sediments reveal billions of years of Martian geological history, akin to the pages in a stone book. Some layers contain water-altered minerals, supporting hypotheses that liquid water once traversed the canyons.
Mysterious dark streaks have also been found on some canyon walls that appear in warm seasons and then disappear when it cools down. These recurrent slope lineae may be evidence of seasonal flows of salty water, although questions persist about their nature.
The Caloris Basin: Mercury’s Largest Impact Scar
Between 2011 and 2015, when the MESSENGER spacecraft circled Mercury, it took detailed imagery of one of the solar system’s largest impact basins. The Caloris Basin is some 960 miles wide—wider than Texas. An impact that would have formed such a large crater like this one took place about 3.9 billion years ago, when an enormous asteroid hit Mercury’s surface.
The impact generated energy equal to a quadrillion nuclear bombs, sending shock waves across the entire globe. On the far side of Mercury, those shockwaves collided and threw heat-shattered terrain into complete disarray in a hilly, valley-laden orbit for some time. This “antipodal disruption” is evidence of how violent the impact was.
The interior of the basin is covered with volcanic plains that subsequently flooded the crater floor, and can be seen to have formed smooth areas across which there are small impact craters. The rim of the basin hosts multiple rings—concentric mountain ranges that formed as bundles of shockwaves from the impact converged on their journey across Mercury’s crust. These rings are like the lines you observe when you throw a stone into water.
The basin is named for the Latin word for heat, “Caloris.” When imaged for the first time by Mariner 10 in 1974, the basin was at a Mercury “hot longitude”—one that lies between the two points where it is closest to our host star along its elliptical orbit.
The Caloris Basin is imaged by scientists to learn about large impact craters and their influence on planetary geology. The basin’s structure and volcanic infill give hints about the interior of Mercury and how heat has been distributed through time. The existence of small, irregular depressions with bright interiors, which the scientists call hollows, reveal that geological processes driven by solar heating and volatile loss are still underway.
Enceladus’s Tiger Stripes: Ice Geysers from an Alien Ocean
Enceladus, a moon of Saturn, encases within its icy shell one of the most riveting discoveries that we have made so far in our solar system: a global ocean of liquid water. The Cassini spacecraft uncovered this secret while hunting for oddball features near the moon’s south pole: four fissures that run in parallel and are informally known as “tiger stripes.”
These 80-mile-long cracks light up with infrared heat, signaling that they are warmer than the surrounding terrain. Even more astonishingly, Cassini captured tremendous plumes of water vapor and icy particles from these fractures, jetting hundreds of miles into space. These geysers spray at speeds as high as 800 miles an hour, and some of the material escapes Enceladus’s gravity to refill Saturn’s E-ring.
The tiger stripes are indicative of ongoing cryovolcanism—volcanic activity featuring ice and water, rather than molten rock. The fractures behave like natural pressure valves, allowing water from the subsurface ocean to shoot out through undersea fissures in the ice shell that is 20 miles thick. The moon is flexed by gravitational forces from Saturn, which generate heat that keeps the ocean liquid and powers the eruptions.
Cassini plunged directly through the plumes several times, studying their composition. The spacecraft spotted water vapor, ice crystals, salts, silica particles and some complex organic molecules—the kinds of ingredients that could be used to sustain life. This discovery turned Enceladus from just another moon into one of the most inviting places to look for alien life.
The intensity of the plumes grows as Enceladus passes some locations in its orbit around Saturn. This correlation supports the idea that tidal forces drive the eruptions, acting somewhat like a stress ball: they squeeze out all of the moon’s gassy bits, and when they are greatest, they open up more fractures.
The Lakes and Seas of Titan: Liquid Methane Landscapes
It is the only world we know of, other than Earth, that has stable bodies of liquid on its surface. But the lakes and seas of Titan are not full of water—they’re composed of liquid methane and ethane, hydrocarbons that are gases in Earth’s atmosphere but liquid on Titan, where it’s cold enough (-290°F/-179°C) to make water ice hard as granite.
The radar on the Cassini orbiter cut through the thick, smoggy haze of Titan to map dozens of lakes and seas, virtually all of them near the north pole. The biggest, Kraken Mare, is about 154,000 square miles—larger than the Caspian Sea and equivalent in size to all five Great Lakes combined. The second largest among these is Ligeia Mare, which in some places has been found to be more than 560 feet deep.
These systems of flowing liquid form a water cycling system analogous to Earth but fueled by methane. From the spacecraft, researchers have spotted telltale signs of downpours, river channels, coastlines with rounded cobbles and seasonal shifts in lake levels. There are some small lakes that seem to disappear during summer and then fill with water in other seasons.
The Huygens probe, which penetrated Titan’s atmosphere in 2005, imaged drainage networks etched on the surface of Titan that resemble river systems on Earth. Although the probe touched down on solid ground, its instruments sensed moisture in the form of liquid methane just under the surface where it was probably seeping into substrate like groundwater.
Lakes on Titan have interesting shapes, with islands and peninsulas, and what may be floored basins that could dry up. Some lakeshores show bright, reflective deposits that scientists suspect could be organic compounds left behind by the liquid as it evaporates, much like salt flats on Earth. Radar measurements indicate that the lakes are at least several hundred feet deep and range in depth from shallow puddles to bodies of water more than 100 meters deep.
Miranda’s Chevron-Shaped Coronae: Frankenstein Moon
When Voyager 2 swung by Uranus’s moon Miranda in 1986, it photographed one of the oddest surfaces in the solar system. Miranda has a patchwork appearance that caused some researchers to give it the nickname “Frankenstein moon.” The surface is covered with big, chevron-shaped features known as coronae—places where the ground looks wholly unlike the land around it.
The largest of these coronae, Inverness Corona, is fluted with V-shaped ridges and valleys spread over several hundred square kilometers. These characteristics tower up to 3 miles, shaping immense cliffs and escarpments. One cliff on Miranda, called Verona Rupes, falls some 12 miles—more than double the depth of the Grand Canyon and the tallest known cliff face in the solar system.
Originally, researchers had proposed that Miranda was shattered by impacts and reassembled, which would account for the jumbled surface. But the prevailing idea is that the coronae are shaped by tectonics brought on by tidal heating. As Miranda swirled around Uranus, in resonance with other moons orbiting the planet, gravitational tugging caused the moon’s interior to flex and stretch; melting ice let denser material rise up from below.
The coronae exhibit grooves and ridges that look like race tracks, with parallel features extending for dozens of miles at a time. The most likely explanation was that warm ice from below had pushed upward, causing the cold surface ice to break along these patterns. It’s something like how ice floes break apart and move around the polar regions of Earth, although at a planetary scale.
Miranda’s small size—only 290 miles across—adds even more surprise to its dramatic features. The moon is so small that if you could jump off Verona Rupes, it would take you about 10 minutes to hit the bottom because of its weak gravity.
The Great Red Spot: Jupiter’s Giant Storm From Above
Strictly speaking not a landform, but an atmospheric feature, the Great Red Spot on Jupiter is one of those features that has transfixed viewers since it was first observed in the 1600s. This counterclockwise-spinning storm is roughly 10,000 miles across—big enough to envelop Earth with room to spare. Winds at its periphery rise to 270 miles an hour.
Juno, the NASA spacecraft currently orbiting Jupiter, has for the first time ever shared a view of its neighbor’s most iconic feature: the Great Red Spot. The structure is a colossal feature that extends roughly 5 miles above the surrounding cloud deck. Its redness is probably caused by complex organic molecules that form when ultraviolet sunlight breaks up simple chemicals in Jupiter’s upper atmosphere.
The spot has been shrinking steadily since precise measurements began in the 1800s. The historical records indicate that at a certain point it was double its current size, larger than 25,000 miles in diameter. The reasons behind this shrinkage are still unknown, but researchers are keeping an eye on the storm to see how it develops.
Instruments on Juno have shown that the Great Red Spot reaches far down into Jupiter’s atmosphere—at least 200 miles under the visible cloud tops. That makes it not just a surface feature, but rather a big swirling column of gas deep in the planet.
The storm’s persistence leads to fascinating questions. Hurricanes on Earth wind down when they reach land or run out of an energy source. Unlike hurricanes on Earth, Jupiter has no solid surface to stop the storm and it feeds off the planet’s internal heat instead of ocean water. This partnership also is what enables the Great Red Spot to continue for hundreds of years, maybe even thousands.
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The Huygens Landing Site: Titan’s Cobblestone Shoreline
When the Huygens probe landed on Titan in January 2005, it was the first to land on a world beyond the inner solar system. The landing site showed a few large, round “rocks.” They appeared pretty much like the cobblestones you’d find on your everyday terrestrial beach—except these rocks were not of stone. They were probably water ice boulders, rounded by tumbling in flowing liquid methane.
For two and a half hours, Huygens plummeted through Titan’s dense atmosphere, taking pictures all the way down that revealed drainage channels cut into the surface of Titan. These drainages then joined into one larger system as they carried over downslope, just like water drainage systems on Earth. The terrain indicated that liquid had flowed relatively recently in terms of geology.
The probe landed on a relatively flat place that had a thin crust over more solid ground underneath. Instruments sensed a temporary liquid presence as the heat of the probe warmed its surroundings, hinting at moisture beneath, but not at, the surface (either in the form of liquid methane or pentane-saturated substrate). The texture was described as being similar to wet sand or mud.
Surface imagery revealed intermittent ice boulders from 2 to 8 inches in diameter, smoothed by abrasions. The fact that the objects were rounded, not angular, indicated they had been tumbled by flowing liquid that wore down their edges over time. The gaps and orientation of these cobbles looked just like dry water courses on Earth left behind when floodwaters drain away.
Temperature and pressure readings taken on the landing site showed that liquid methane is possible on Titan’s surface, as is rain—albeit sporadically. The evidence strongly supports Titan as having thousands of long years-long dry periods bracketed by intense rainstorms composed of methane, the process similar to flash floods in our desert areas on Earth.
Nitrogen Geysers on Neptune’s Moon Triton: Neptune’s Cold Satellite
Neptune flyby in 1989 by Voyager 2 included the closest approach to that planet’s largest moon, Triton. Researchers thought they’d discover a cold, dead world, but instead Voyager discovered active geysers sending material flying from the surface—an awe-inspiring find on one of the coldest objects in the solar system at -391°F (-235°C).
These gaseous and dark organic compounds are blasted 5 miles high into Triton’s tenuous atmosphere from the cryovolcanic eruptions. Winds then blow the material horizontally more than 90 miles before it lands, causing the dark streaks we can see from space. Voyager spotted four or more active geysers during its brief visit.
Triton features an interesting geological characteristic termed “cantaloupe terrain,” a surface of pits and ridges that look like cantaloupe skin. This weird surface likely developed from diapirs, where warmer ice rose up through the crust in blobs like those of a lava lamp, giving it that pockmarked look.
That the moon orbits Neptune backward—opposite to the planet’s rotation—supports the idea Triton was captured from the Kuiper Belt rather than born alongside Neptune. Such a capture process would have led to the intense tidal heating capable of generating a subsurface ocean. And while that ocean has probably frozen, heat left over might still be powering the nitrogen geysers.
The southern cap of Triton appears bright pink in color due to the mixture of nitrogen ice and methane. Nitrogen ice evaporates at one pole and condenses at the other, and over Triton’s 165-year seasonal cycle, this slow but constant process coats the moon in a fresh layer of frost. This seasonal frost migration also has the effect of causing the moon’s already tenuous atmosphere to thicken and thin in a matter of decades.
Comparison of Major Planetary Landforms
| Feature | Location | Type | Size | Discovery Year | Key Characteristic |
|---|---|---|---|---|---|
| Olympus Mons | Mars | Shield Volcano | 13.6 miles (16 km) high, 374 miles (600 km) wide | 1971 | Tallest mountain in solar system |
| Valles Marineris | Mars | Canyon System | 2,500 miles long, 4 miles deep | 1971 | Largest canyon system |
| Caloris Basin | Mercury | Impact Crater | 960 miles diameter | 1974 | Caused antipodal disruption |
| Tiger Stripes | Enceladus | Cryovolcanic Fractures | 80 miles long | 2005 | Active water plumes |
| Kraken Mare | Titan | Liquid Methane Sea | 154,000 square miles | 2006 | Largest known lake beyond Earth |
| Inverness Corona | Miranda | Tectonic Feature | Hundreds of square kilometers | 1986 | V-shaped ridges and valleys |
| Great Red Spot | Jupiter | Storm System | 10,000 miles wide | 1600s | Centuries-old anticyclone |
| Huygens Landing Site | Titan | Riverbed/Shoreline | Local area | 2005 | Ice “cobblestones” |
| Nitrogen Geysers | Triton | Cryovolcanoes | 5-mile (8 km) high plumes | 1989 | Active in extreme cold |
The Lessons These Landforms Teach About Planetary Science
These nine glorious landforms are about more than pure aesthetics: they’re essential evidence for how planets evolve and transform over billions of years. Every feature has a tale to tell of the forces that built that world, and its origins in our planet’s history.
Volcanic features such as Olympus Mons and the tiger stripes of Enceladus show off internal heat sources. Mars’s gargantuan volcano gives us a glimpse of what happens when a planet doesn’t have plate tectonics but still has volcanic activity. Enceladus is evidence that even tiny, remote moons can host liquid water oceans with help from tidal heating—a finding that broadens our ideas of what constitutes habitable conditions.
Impact features such as the Caloris Basin reveal much about the dynamic and violence-prone early solar system, where Pluto-sized and larger asteroids, plus comets, pummeled the planets and their moons. Craters’ size and distribution aid scientists in determining surface ages—older ones are pock-marked with more craters, while younger places weather the impacts better.
Erosional landforms like Valles Marineris and Titan’s river channels show that, when it flows, liquid can shape landscapes—be it water, methane or nitrogen. These features enable us to recreate ancient climates and learn how atmospheres and surfaces interact.
Tectonic features such as Miranda’s coronae are evidence that internal heat can be a source of geological activity in small bodies well away from the Sun. The strange landscapes on Miranda raise questions about our ideas of where and when geologic activity can take place.
Large-scale atmospheric phenomena like Jupiter’s Great Red Spot provide a window into the intricate dynamics at play in giant planet atmospheres. Understanding these storm systems allows us to model weather on Earth and maybe even find storms on planets that circle other stars.
The Contribution of Spacecraft in the Detection of These Marvels
Robot spacecraft are how we found these things in the first place. Based on the photographs and videos of both the early Mariner and Viking missions to recent explorers such as Cassini and Juno, these machines that provide us with eyes in places we cannot (yet) go are nothing short of extraordinary.
With each generation of spacecraft come better cameras, sensors and instruments. The 1970s Mariner missions showed basic features with television cameras and crude spectrometers. Nowadays, such spacecraft as the Mars Reconnaissance Orbiter have high-resolution cameras that can spot objects the size of a car from orbit and radar instruments that can peer into planetary crusts and mantles.
Orbiting spacecraft can track changes over time, observing as Martian gullies form and seasonal frost advances and retreats on Triton and lakes on Titan evaporate and refill. This time-based view is the fourth dimension to our knowledge of planetary geology.
Landing missions such as Huygens and the different Mars rovers provide a ground-based view that complements orbital measurements. These surface missions can study rocks directly, take wind and temperature measurements, and record conditions in a manner that orbiters cannot.
The next sets of missions offer even more spectacular discoveries. Europe’s Dragonfly—a nuclear-powered drone that will study Titan from the mid-2030s by hopping around to make direct science on its methane cycle and organic chemistry—will focus on clearing clouds and worlds on methane-based life. Europa Clipper will fly by Jupiter’s moon Europa multiple times as it investigates another subsurface ocean world. These coming missions will certainly reveal landscapes we can hardly even imagine.
For more information about ongoing space missions and discoveries, visit NASA’s Solar System Exploration.
Frequently Asked Questions
What planet has the most varied topography in the solar system?
Possibly, it is Mars, with its enormous volcanoes and deep canyons, impact craters and sand dunes on a scale unmatched by anything on Earth—not to mention polar ice caps and the relics of ancient river valleys and perhaps even mudflows. The diversity results from Mars’s complex geologic history, including volcanism, water tracking across the surface, glaciation and impacts.
Could any of these structures be home to life?
The favorites are Enceladus’s tiger stripes and Titan’s methane lakes. Enceladus’s underground ocean contains liquid water, salts and organic molecules—ingredients that, here on Earth at least, are necessary for life. Titan’s chemistry could support life that was not carbon-based and in some way adapted to live on liquid methane instead of water, but this is all speculative.
Why do some worlds have far more extreme features than others, including Earth?
Several factors contribute to this. Less gravity means structures such as Olympus Mons can rise higher before they fall down. No plate tectonics on Mars means volcanic hotspots stay put and big mountains are built. Various erosion patterns are produced due to different atmospheric situations. Both the composition of a planet and its level of internal heat shape what geological processes take place, and how dramatic they become.
How do they know the age of these features?
Crater counting—older surfaces have been pummeled for longer by meteors. The layering in canyons, like Valles Marineris, gives relative ages: deeper is older. Some methods are based on counting how fast things erode, or how fast certain substances blacken when bombarded with radiation. These techniques yield estimates, not precise ages.
Will humans ever set foot on these landforms?
Missions to Mars appear increasingly likely in the next three decades, which would potentially see astronauts visiting Olympus Mons or Valles Marineris. And farther-flung places such as Titan or Enceladus present even more formidable obstacles in the form of isolation and environmental hostility; humans will probably be a long time visiting. But more advanced robots will keep on poking around these wonders for us.
What do these findings teach us about Earth?
The study of other worlds allows us to better understand Earth by making comparisons. We discover what makes our planet special—plate tectonics, lots of liquid water, a protective magnetic field. We also know that there are universal geological processes that play out on many worlds, from volcanism to erosion. Such comparisons also help clarify Earth’s own geological past and potential future.
Looking Toward Future Discoveries
The nine features described here are just a tiny fraction of the geological marvels that robotic and crewed spacecraft have spotted across the solar system. Every mission brings new surprises, challenging our beliefs and enriching our appreciation of planetary science.
Future missions will visit worlds we have scarcely even seen. The upcoming James Webb Space Telescope is set to start to measure the atmospheres of planets elsewhere in the galaxy, and may be able to detect exotic atmospheric components on others’ habitable-zone worlds. Missions to the ice giants Uranus and Neptune have been advocated which would follow up on their mysterious moons.
Commercial players are now engaging in planetary exploration side by side with government space agencies, which might speed the rate of discovery. As new technologies, such as the CubeSat (an affordable and miniature design for satellites), make it less costly to visit, expeditions can take place more often and study specific questions or track evolving environmental changes.
As our capability to study space with spacecraft advances and our understanding grows, the line between Earth science and planetary science becomes ever more indistinct. We’re finally coming to the realization that Earth is an example of a planet, not the only one. Understanding the geological processes on Mars allows us to understand deserts on Earth. Investigations of the methane cycle on Titan contribute to an understanding of hydrocarbon deposits as they are envisioned in petroleum geology.
The Wonder of Alien Landscapes
These nine beautiful landforms are a reminder that our solar system is full of worlds both wondrous and strange. From mountains three times the height of Everest to lakes of liquid methane, from perpetual storms to geysers spewing ice into space, our cosmic backyard is full of sights that would be more at home in a movie than out our window.
Every picture spacecraft send back is a victory of human curiosity and engineering. These machines transport us for years on end through the hostile environment of space, and withstand high radiation levels and temperatures to perform with accuracy to capture images and data that alter our understanding of the universe.
The landforms also inspire humility. That’s no small thing; Earth may be precious and unique in its life-hosting nature, but it adheres to geophysical rules that can be found throughout the solar system. Gravity shapes mountains everywhere. The flowing liquids cut channels on any world with a good atmosphere. Craters are made by impacts, irrespective of a planet’s makeup. These universal habits bridge Earth and remote worlds, implying that the laws of physics and chemistry give rise to the same shapes wherever they operate.
And as spacecraft keep on looking around our solar system and beyond, they’re bound to find landforms even more amazing than those described here. Each generation comes to share a new set of images that stretch the imagination, enhance our understanding and help us appreciate the dynamic, complex worlds around us—in any cosmic backyard. The era of planetary exploration has only just begun, and the best discoveries are probably still waiting for us amid the planets, their moons and the asteroids that orbit our Sun.
A line of these nine, awe-inspiring landforms does not mark an ending but a beginning—the first chapter in what will be humanity’s ongoing story to explore and comprehend the variety of worlds that are part of our solar system… and one day soon, even those galaxies beyond.
