Venus looks so earthlike yet is so fundamentally different
Across the scorched face of Venus, 741 massive circular scars — called coronae — have long puzzled those who study the inner lives of planets. Now, a team led by planetary scientist Anna Gulcher has used decades-old radar echoes from NASA's Magellan spacecraft to build three-dimensional portraits of these formations, finding in them the fingerprints of a restless mantle and the absence of the one geological gift that made Earth livable. The work is less a story about Venus than a meditation on contingency — on how the presence of oceans, and the plate tectonics they enable, may be the slender thread separating a habitable world from a molten one.
- Venus hosts 741 colossal ring-shaped fracture systems — some wider than the continental United States — whose origins have resisted explanation for decades.
- New 3D modeling of Magellan radar data reveals these coronae are surface scars left by hot mantle plumes pushing upward from deep within the planet, making Venus' interior far more geologically restless than previously assumed.
- The diversity among coronae — some active, some dormant, formed by different mechanisms — suggests Venus operates under no single tectonic rule, and current instruments may be missing significant geological activity entirely.
- Without water oceans to weaken its crust, Venus never fractured into moving plates, leaving carbon dioxide to accumulate unchecked and the planet to cook itself into uninhabitability over billions of years.
- Missions VERITAS and EnVision are being prepared to arrive at Venus with instruments sharp enough to finally distinguish ancient geological relics from processes still reshaping the planet today.
Venus carries across its surface 741 massive circular formations — coronae — ranging from 60 to more than 2,100 kilometers wide. Planetary scientist Anna Gulcher and her team at the University of Freiburg spent years reexamining radar data from NASA's Magellan spacecraft, presenting their findings this spring at the European Geosciences Union assembly in Vienna. What they found suggests a planet whose interior is far more turbulent than once believed.
The coronae are not random. Their near-perfect circular geometry, ringed by outward-radiating fractures, points to a common origin: plumes of hot rock rising from Venus' mantle, pressing the crust upward into these distinctive rings. By layering gravity measurements, topographic data, and geodynamic simulations, Gulcher's team identified likely warm mantle upwellings beneath 52 of the structures. But the coronae vary — some appear active, others ancient, formed through different processes — hinting at a spectrum of tectonic behavior that current instruments may not fully capture.
The deeper question the coronae raise is why Venus and Earth, near-twins in size and composition, arrived at such different fates. On Earth, vast oceans seep into the crust, softening rock enough for the lithosphere to fracture into moving plates. That plate tectonic system recycles carbon back into the mantle, keeping the atmosphere in balance and the surface habitable. Venus, apparently never graced with large oceans, kept a crust too rigid to break apart. Carbon accumulated, temperatures climbed, and any water that may have existed burned away.
What unsettles Gulcher most is the paradox: Venus' surface looks strikingly Earth-like in its geological complexity, yet the planet is fundamentally, lethally different. Two forthcoming missions — VERITAS and EnVision — will map Venus with far greater precision, potentially revealing whether its coronae are fossils of a more active past or evidence of processes still unfolding. In reading the scars on Venus, scientists are tracing the narrow conditions that allowed one planet to become a home for life — and another to become its opposite.
Venus wears a crown of scars that planetary scientists are only now beginning to read. These are the coronae—massive, concentric rings of fractured rock scattered across the planet's surface, some as wide as the continental United States. A team led by Anna Gulcher, a planetary scientist at the University of Freiburg, has spent years combing through decades-old radar data from NASA's Magellan spacecraft to understand what these strange formations are telling us about Venus' hidden interior. The work, presented this spring at the European Geosciences Union assembly in Vienna, suggests that Venus' geology is far more dynamic than we once thought—and that it reveals something crucial about why Earth became habitable while our sister planet did not.
The coronae are not random scars. Gulcher's team catalogued 741 of them across Venus' surface, ranging from 60 kilometers to more than 2,000 kilometers in diameter. The largest, Artemis Chasma, stretches 2,100 kilometers across—large enough to span from the Rocky Mountains to the Pacific coast. What makes these formations remarkable is their geometry. They are almost perfectly circular, ringed by fractures that radiate outward like the spokes of a wheel. This geometry is no accident. Gulcher believes the coronae are surface expressions of something happening deep below: plumes of hot rock rising from Venus' mantle, pushing the crust upward and creating these distinctive rings. It is mantle convection made visible—the slow, grinding circulation of planetary material that shapes worlds from within.
But here is where the story becomes complicated. Not all coronae are the same. Some show signs of different formation mechanisms. Some appear to be active; others seem dormant or ancient. By combining gravity measurements with topographic data and running geodynamic simulations, Gulcher's team identified possible warm mantle upwellings beneath 52 coronae. This diversity suggests that Venus' interior is not operating under a single, simple rule. Instead, multiple processes are at work—a spectrum of tectonic activity that current gravity measurements may not even be capturing fully. There could be more activity on Venus than we can currently detect.
This matters because of what it tells us about the difference between Venus and Earth. Both planets are rocky, both are roughly the same size, both began with similar compositions. Yet Earth became a world where life emerged and flourished, while Venus became a hellscape with surface temperatures hot enough to melt lead. The key difference, Gulcher argues, lies in plate tectonics—the grand recycling system that has operated on Earth for at least three billion years. On Earth, the lithosphere is broken into giant moving plates that collide, separate, and slide past one another. This constant motion drives volcanic activity, creates mountain ranges, and crucially, recycles carbon back into the mantle. Without this recycling, carbon dioxide would accumulate in the atmosphere, trapping heat and making the planet uninhabitable.
Venus, it appears, never developed this system. The reason likely comes down to water. On Earth, vast oceans cover the surface, and water seeps into the crust, making the rock weaker and more pliable. This weakness allows the lithosphere to break apart into movable plates. Venus, by contrast, appears to have never had large oceans. Without water to soften the crust, the rock remained too rigid to break into plates. Instead, Venus may have relied on limited carbon recycling through mantle convection and volcanic resurfacing—processes that were simply not efficient enough to keep the atmosphere in balance. Over billions of years, carbon accumulated, temperatures rose, and any water that may have existed evaporated away.
What haunts Gulcher most is the paradox at the heart of this story. Venus' surface structures look remarkably Earth-like in many ways. The coronae themselves suggest dynamic geological processes, the kind of thing we associate with a living, active world. Yet beneath that surface similarity lies a fundamentally different planet—one that lacked the crucial mechanism that allowed Earth to remain stable and habitable. We see structures on Venus that are so earthlike yet also show very important differences, Gulcher has said. With the available data, we don't fully understand how it can look so similar but be so different.
The mystery may soon begin to yield. Two upcoming missions—VERITAS and EnVision—will arrive at Venus with far more sophisticated instruments than Magellan carried. They will map the planet's surface and subsurface with unprecedented resolution, measure gravity with greater precision, and potentially detect active tectonic signals that current data cannot resolve. These missions may finally answer whether Venus' coronae are relics of a more geologically active past, or whether they represent ongoing processes that continue to reshape the planet today. They may also help us understand whether similar plume-driven tectonics operated on the early Earth, before plate tectonics took over. In studying Venus' crown, we are learning not just about another world, but about the narrow conditions that allowed our own world to become a home for life.
Citas Notables
They are huge circles of fracture systems that we think are basically the surface expression of a plume of hot material moving upwards from the interior of the planet.— Anna Gulcher, University of Freiburg
We see structures on Venus that are so earthlike yet also show very important differences. With the available data, we don't fully understand how it can look so similar but be so different.— Anna Gulcher
La Conversación del Hearth Otra perspectiva de la historia
Why should we care about these crown-shaped formations? They're on another planet.
Because they're a window into why Earth is alive and Venus is not. The coronae tell us how planets work at their deepest levels—how heat moves, how rock breaks, how atmospheres either stabilize or run away. Understanding Venus helps us understand what made Earth special.
So these coronae are caused by hot material rising from inside the planet?
Yes. Imagine a plume of magma pushing upward through the crust, hotter and less dense than the rock around it. As it rises, it lifts the surface, creating these circular rings of fractures. It's the planet's interior writing on its skin.
And Earth doesn't have these?
Earth has mantle plumes too, but they're hidden beneath moving tectonic plates. On Venus, there are no plates—just a rigid, unbroken crust. So the plumes create these visible scars instead.
Why didn't Venus develop plate tectonics?
Water. Earth's oceans soaked into the crust, making the rock weak enough to break apart into plates. Venus never had oceans—we think because it was always too hot. Without water, the crust stayed rigid. No plates meant no efficient carbon recycling. Carbon built up in the atmosphere, temperatures climbed, and the planet became uninhabitable.
So these coronae are telling us Venus is geologically dead?
Not necessarily dead—possibly still active. But they're telling us Venus is geologically isolated. Its interior processes can't regulate its atmosphere the way Earth's can. That's the real story these formations are revealing.
What happens next?
New missions arrive soon with better instruments. They'll see whether these coronae are still changing, still active. They might finally answer why two similar planets took such different paths.