Mars is famous for one color above all others: red. Its rusty landscapes, dusty plains and rocky mountains have earned it the nickname the Red Planet. But Mars is far more colorful than that familiar image suggests.
New images of the planet’s southern polar region reveal an unusual landscape filled with purple, pink, red and bluish shades. At the center of this striking scene is Thyles Rupes, a huge icy cliff system with cliffs rising more than 1 kilometer (0.6 miles) high.
The unusual colors are not simply an optical illusion. They reveal a complicated mixture of volcanic rock, dust, frozen carbon dioxide and seasonal frost. Together, these materials create one of the most unusual-looking landscapes on Mars.
Why Is Mars Usually Red?
The dominant color of Mars comes from iron-rich minerals in its rocks and dust. Over time, iron reacts with oxygen and becomes oxidized, producing compounds similar to rust on Earth.
This iron oxide spreads across the Martian surface and atmosphere as fine dust. When sunlight reflects from this dusty surface, Mars takes on its familiar reddish-orange appearance.
However, the south polar region contains a much wider variety of materials. That is why spacecraft cameras can capture colors that look very different from the usual Martian red.
The purple and pink appearance comes from a combination of dust, frost, ice and different types of rock interacting with sunlight.
A Landscape Made of Different Materials
The darker areas visible in the region are linked to volcanic material. Mars was volcanically active in its past, and volcanic rocks spread across large areas of the planet.
Some of these rocks contain minerals such as olivine and pyroxene.
Interestingly, these minerals are also found deep inside Earth. Olivine contains magnesium, iron and silicate, while pyroxenes are a large family of silicate minerals containing mainly silicon and oxygen.
On Earth, minerals like these are important components of the planet's mantle. On Mars, they provide scientists with clues about the planet's volcanic history and the composition of its interior.
The different minerals absorb and reflect sunlight differently, helping create variations in color across the Martian surface.
The Blue Areas Are Frozen Carbon Dioxide
One of the most surprising parts of the image is the presence of pale bluish regions.
These areas are largely associated with frozen carbon dioxide, commonly called dry ice.
Mars has an extremely thin atmosphere, and carbon dioxide is its main atmospheric gas. Near the south pole, temperatures can become cold enough for atmospheric carbon dioxide to freeze directly onto the surface.
Unlike ordinary water ice, this seasonal carbon dioxide frost can appear and disappear as the Martian seasons change.
The image was captured during spring, yet some carbon dioxide frost was still present around the south polar region.
The larger pale area at the lower part of the scene is connected to the south polar cap. Mars has a permanent polar cap, but it is surrounded by a seasonal layer of carbon dioxide frost that expands during winter and shrinks as the planet moves toward warmer seasons.
Why Does Mars Look Purple?
So where does the unusual purple color come from?
It is not because Mars suddenly has purple rocks everywhere.
Instead, the overall appearance results from several things happening at once.
Fine dust floating in the Martian atmosphere can affect the way sunlight reaches the surface. At the same time, frost can cover the ground, while patches of ice and dust can mix together.
Even the time of day matters.
The angle of sunlight changes throughout the Martian day, altering how different surfaces reflect light. Soft morning illumination, surface frost and atmospheric dust can combine to produce the pinkish-purple appearance captured by spacecraft cameras.
In other words, Mars does not necessarily look exactly like this all the time. Its appearance can change with season, lighting, frost and atmospheric conditions.
Mars Also Has Unusual Dunes
The region contains another interesting feature: dunes.
Mars is famous for its enormous fields of wind-shaped sand. But the dunes in this particular region are not always as smoothly sculpted as those found elsewhere.
That is partly because the winds near the south pole can come from different directions.
Among the formations are structures known as barchanoid ridges. These are curved, arc-shaped dune formations that resemble some dunes found in Earth's deserts.
They can develop horn-like extensions pointing in the downwind direction.
Their presence provides another clue about how Martian winds move material across the surface.
A Giant Cliff With an Unusual Origin
One of the most dramatic features in the image is Thyles Rupes, a vast cliff system extending for hundreds of kilometers.
The word Rupes comes from Latin and means cliff. The name Thyles refers to Thule, a mythical far-northern land described by ancient writers.
The cliffs of Thyles Rupes can rise more than a kilometer above the surrounding terrain, making them an impressive feature even on a planet filled with enormous mountains and valleys.
But how did such a huge structure form?
The answer is particularly interesting because Mars does not have Earth's active plate tectonics.
Mars Is a One-Plate Planet
On Earth, enormous mountain ranges can form when tectonic plates move and collide. The Himalayas, for example, continue to rise because tectonic plates are pushing against each other.
Mars works differently.
Scientists generally describe Mars as a single-plate, stagnant-lid planet. Its outer crust is not divided into moving tectonic plates like Earth's.
So Thyles Rupes probably did not form through the same kind of plate collision that creates Earth's major mountain ranges.
Instead, scientists think its formation may be connected to the cooling of Mars's interior.
As the planet gradually lost heat, its interior contracted. This cooling process could have placed enormous stresses on the crust. In some areas, parts of the crust were pushed upward, creating large ridges and cliffs.
This means that a feature that looks somewhat like a mountain or tectonic structure may actually be a record of Mars slowly cooling over billions of years.
Spacecraft Are Changing Our View of Mars
Much of what we know about these landscapes comes from spacecraft orbiting Mars.
The European Space Agency's Mars Express has been studying the planet since 2003, while NASA's Mars Reconnaissance Orbiter has provided extremely detailed observations of the Martian surface.
These spacecraft have allowed scientists to examine areas that would be extremely difficult to study from the ground.
Instead of seeing Mars simply as a red, dusty world, researchers can now identify different minerals, ice deposits, dunes, cliffs and geological structures from orbit.
Every new image can therefore reveal another piece of the planet's history.
The Red Planet Is More Colorful Than We Thought
Mars may look like a simple red world from a distance, but its surface tells a much more complicated story.
Its southern polar region contains volcanic minerals, iron-rich dust, frozen carbon dioxide, seasonal frost, dunes and enormous cliffs. Their combination produces the surprising purple and pink landscape captured from orbit.
And the story behind those colors is even more fascinating. They reveal how Mars has been shaped by volcanism, atmospheric processes, seasonal changes and the slow cooling of its interior.
Mars may no longer have the active geology of Earth, but its surface is far from boring. Every layer of dust, every patch of frost and every giant cliff preserves evidence of a planet that has been changing for billions of years.
The Red Planet, it turns out, has a purple side—and spacecraft are finally giving us a chance to see it.
Reference: https://www.esa.int/Science_Exploration/Space_Science/Mars_Express/Purple_swirls_on_the_Red_Planet
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