Why Mountains on Mars Tower Over Those on Earth and the Moon

Mount Everest, the highest mountain on Earth, rises 8,848 meters above sea level. But on a planetary scale, Everest is modest. On Mars, Olympus Mons towers more than 21 kilometers high, making it the tallest mountain known in the solar system. A recent scientific study explains why such dramatic differences exist — and what ultimately limits how tall mountains can grow on Earth, the Moon, and Mars.

The research, titled “What is the maximum elevation mountains can reach on Earth, the Moon, and Mars?”, was conducted by Eulogio Pardo-Igúzquiza, a geoscientist at the Institute of Geosciences in Spain, and Peter Dowd, a professor of geostatistics at the University of Adelaide in Australia. Their work examines how gravity, rock strength, and geological processes combine to set natural limits on mountain height across different planetary bodies.

“Mountains grow until the forces lifting them are balanced by the forces trying to destroy them,” the researchers wrote. “That balance depends strongly on planetary gravity and internal dynamics.”

Earth: Tall Mountains Under Constant Attack

On Earth, mountains are shaped primarily by plate tectonics and volcanism. The Himalayas continue to rise as the Indian Plate collides with the Eurasian Plate, pushing crust upward. But that growth is slow and constrained.

Earth’s relatively strong gravity places enormous pressure on the rocks beneath large mountain ranges. As mountains grow taller, their own weight causes the crust to weaken and spread laterally. At the same time, erosion relentlessly wears mountains down.

Rain, rivers, glaciers, landslides, and wind constantly remove material from mountain slopes and peaks. According to the study, this combination of uplift and erosion creates a dynamic equilibrium.

“As mountains rise, erosion accelerates,” Pardo-Igúzquiza and Dowd explained. “Eventually, the system reaches a limit beyond which additional height cannot be sustained.”

As a result, Earth’s mountains rarely exceed 9 to 10 kilometers in total elevation. Mount Everest remains the highest peak above sea level, while Mauna Kea in Hawaii is taller when measured from its base on the ocean floor, though much of it lies underwater.

The Moon: High Peaks Without Geological Renewal

The Moon presents a stark contrast. It has no oceans, no active plate tectonics, and almost no atmosphere. Without sea level, scientists measure lunar elevation relative to the Moon’s average surface.

Using laser altimetry data from orbiting spacecraft, researchers have identified the Moon’s highest point — known as the Selenean summit — which rises about 10.6 to 10.8 kilometers above the lunar mean surface. That makes it slightly higher than Everest when compared within each body’s own reference system.

But appearances can be misleading. According to Dowd, lunar mountains are not built by continuous internal forces like those on Earth.

“Most lunar topography is the result of ancient impacts and crustal deformation that occurred billions of years ago,” he said. “Once formed, these structures changed very little.”

The Moon’s weaker gravity allows tall features to persist, but the absence of active geological processes means there is little opportunity for mountains to grow even larger.

Mars: Home of the Solar System’s Giant

Mars is where the rules change dramatically. Olympus Mons, a massive shield volcano, rises at least 21.9 kilometers above the planet’s average surface — nearly three times the height of Everest.

The study identifies several reasons for Mars’ extreme mountain heights. First, gravity on Mars is only about 38 percent as strong as Earth’s, allowing large structures to remain stable. Second, Mars lacks plate tectonics.

On Earth, moving tectonic plates carry volcanoes away from their magma sources. On Mars, volcanic hotspots remain fixed in place, allowing lava to pile up in the same location for millions of years.

Third, erosion on Mars is minimal. The planet’s thin atmosphere and scarcity of liquid water mean that wind and gravity are the primary erosive forces, both far weaker than Earth’s rain- and glacier-driven erosion.

“These conditions allow volcanic edifices like Olympus Mons to grow extraordinarily large,” the researchers wrote.

The Physics Behind Mountain Limits

At the heart of the study is a simple physical principle: rock strength versus gravitational stress. As a mountain grows taller, pressure increases at its base. Once that pressure exceeds the strength of the rock, the mountain can no longer support itself.

This threshold varies depending on gravity and crustal properties. Lower gravity allows taller mountains before failure occurs, while active erosion and tectonics lower the practical limit.

Mars, with low gravity and long-lived volcanism, represents an extreme case. Earth, with strong gravity and aggressive erosion, occupies the opposite end of the spectrum. The Moon falls somewhere in between.

More Than Just a Height Record

According to Pardo-Igúzquiza, understanding mountain height limits helps scientists interpret the geological history of planets.

“Mountains preserve the story of how a planet works,” he said. “By comparing them, we learn why Earth is dynamic and habitable, while Mars preserves enormous but ancient structures.”

The findings also highlight that Earth’s relatively modest mountains are not a weakness, but a sign of an active planet — one shaped by water, atmosphere, and continuous renewal.

Mars may host the tallest mountain in the solar system, but Earth remains unique for the forces that keep its peaks in balance. (Sulung Prasetyo)