Mars facts · Color
Why is Mars red?
Mars is red because its dust is full of rusted iron minerals, iron oxides, and winds spread that dust across the planet. A 2025 study suggests the rust formed early, while Mars still had water.
Updated Sources (13)
What makes Mars red?
Rust in its dust. Iron in Mars’s rocks has, at some point, reacted with liquid water, or with water and oxygen in the air, much as rust forms on Earth, ESA says. Over billions of years that rusty material, iron oxide, was broken down into dust and spread around the planet by winds, which still move it today.[3] Dust kicked up into the air makes the planet look mostly red from a distance, NASA says.[1] Or, as NASA’s site for kids puts it: “It’s red because of rusty iron in the ground.”[2]
That color makes Mars easy to pick out in the night sky.[3] Our Mars tonight page shows where to look.
Is Mars covered in rust?
Its dust is rusty, but Mars isn’t rust all the way through. NASA says the iron is rusting in the rocks, the soil and the dust,[1] and the dust blankets the planet’s surface.[5] Inside, rock can look quite different. In February 2013 NASA’s Curiosity RoverA rover is a robot vehicle that drives across Mars, following plans its team on Earth sends ahead of each drive.More in the glossary photographed the first powder it drilled from a rock: it was gray-green, while the windblown dust and sand left in the same scoop were red. The two colors reflect how oxidized, or rusted, the iron in each sample is.[7]
You can see the same thing from orbit. When whirlwinds called dust devils sweep away the top layer of dust, they leave dark tracks where the material beneath shows through.[8][9]
What did the 2025 study find?
That Mars’s rust may have formed in cool water, early in its history. Scientists had concluded that the iron oxide in the dust was hematite, formed in dry conditions through reactions with the air over billions of years, after Mars’s early wet period, ESA says.[3]
A study published on Feb 25, 2025, in the journal Nature Communications, led by Adomas Valantinas of Brown University, found a better match: ferrihydrite, an iron oxide that contains water.[3][6] The team made replica Martian dust in the lab, ground to about 1/100th the width of a human hair, and compared it with data from NASA and ESA OrbiterAn orbiter circles Mars without landing, studying the planet from above — and many also relay rover data back to Earth.More in the glossary and from rovers including Curiosity and Opportunity.[3][4] “We found that ferrihydrite mixed with basalt, a volcanic rock, best fits the minerals seen by spacecraft at Mars,” Valantinas said.[3]
Why it matters: ferrihydrite typically forms quickly in the presence of cool water, so, ESA says, it must have formed while Mars still had water on its surface. It has stayed stable in today’s dry, cold conditions.[3] “Mars is still the Red Planet,” Valantinas said. “It’s just that our understanding of why Mars is red has been transformed.”[3] What happened to that water has its own page.
This is one study’s conclusion, not the last word. NASA says the idea could be tested for certain once samples from Mars reach Earth.[4] Some of the samples Perseverance has collected include dust, ESA says.[3] But in January 2026 the U.S. Congress’s budget gave no money to the existing Mars Sample Return plan,[13] and ESA’s director general, Josef Aschbacher, said that “at least according to today’s plans, the mission will not go ahead.”[12]
Why is Mars called the Red Planet?
Because of its color, which also gave it its name. The ancient Romans named Mars for their god of war because its reddish color reminded them of blood, NASA says. Other peoples named it for its color too: the ancient Egyptians called it “Her Desher,” meaning “the red one.” It is still often called the Red Planet, NASA says, because iron minerals in the Martian dirt oxidize, or rust, and make the surface look red.[1]
What color is Mars up close?
Many colors, not just red. At the surface NASA lists brown, gold and tan,[1] and ESA points to whites, blacks, yellows, reds, greens and “cappuccino tones”.[9] The 2025 study’s lab-made Martian dust, ferrihydrite mixed with ground basalt, is ochre.[4]
| Layer | Color | Seen in |
|---|---|---|
| Dust and windblown sand | Redrusted iron oxides | PIA16729Curiosity, “Rocknest” residue, Feb 20, 2013 |
| Inside the rock | Gray-greenless oxidized iron | PIA16729Curiosity’s first drilled rock powder, “John Klein” |
| Sand dunes | Darkmostly basalt, a volcanic rock | PIA12289Wirtz Crater, from NASA’s Mars Reconnaissance Orbiter |
| Volcanic ground and dust patches | Dark and lightbasalt-rich ground; lighter patches covered in fine dust | Dark meets light on MarsTerra Cimmeria, from ESA’s Mars Express |
| Sky by day | Hazy reddust in the air | NASA Mars facts |
| Sky at sunset | Blue near the Sunyellow to orange elsewhere | PIA19400Curiosity, Gale Crater, Apr 15, 2015 |
Image numbers are NASA Photojournal IDs. NASA white-balanced the Curiosity scoop photo to show the colors as they would look on Earth.[1][7][8][9][10][11]
What color is the sky on Mars?
Hazy and red by day, with blue around the setting Sun. NASA says the dust in the air would make the sky look hazy and red to our eyes, instead of blue like Earth’s.[1] On Apr 15, 2015, the 956th SolA sol is a day on Mars — 24 h 39 min 35 s, about 40 minutes longer than ours — and rovers count them from the day they land.More in the glossary of its mission, Curiosity photographed its first sunset in color, from Gale Crater.[10] The sky near the Sun is blue; the rest is yellow to orange. The very fine dust lets blue light through slightly more easily and scatters it close to the Sun’s direction, while yellow and red light scatter all over the sky, said Curiosity scientist Mark Lemmon of Texas A&M University.[11] Our Mars weather page has more on dust storms and blue sunsets.
Questions
Why is Mars red?
Because of rust. Iron in its rocks, soil and dust has oxidized, and winds have spread the rusty dust over the planet. From far away, that dust makes Mars look red.
Is Mars covered in rust?
Its dust is rusty, but the rock underneath is less so. When NASA’s Curiosity rover drilled its first rock, the powder inside was gray-green, not red.
Why is Mars called the Red Planet?
Because of its color. NASA says it is still often called the Red Planet because iron minerals in the dirt rust and make the surface look red.
What is Mars named after?
Mars, the Roman god of war. The Romans named the planet for him because its reddish color reminded them of blood, NASA says.
Why does Mars look orange?
It’s the same rusty dust. Up close, NASA says, Mars shows browns, golds and tans as well as red, and the lab-made Martian dust from a 2025 study is ochre.
What color is the sky on Mars?
Hazy and red by day, NASA says, because of dust in the air. At sunset, the sky around the Sun turns blue.
Sources
- NASA Science — Mars: FactsPrimary · checked Oct 6, 2026
- NASA Space Place — All About MarsPrimary · checked Oct 6, 2026
- ESA — Have we been wrong about why Mars is red?Primary · checked Oct 6, 2026
- NASA Goddard Space Flight Center — NASA: New Study on Why Mars is Red Supports Potentially Habitable PastPrimary · checked Oct 6, 2026
- Brown University — Why is Mars red? Scientists may finally have the answerPrimary · checked Oct 6, 2026
- Nature Communications — Detection of ferrihydrite in Martian red dust records ancient cold and wet conditions on Mars (Valantinas et al., Nature Communications, 2025)Primary · checked Oct 6, 2026
- NASA JPL — PIA16729: First Curiosity Drilling Sample in the ScoopPrimary · checked Oct 6, 2026
- NASA Photojournal — PIA12289: The Changing Dunes of Wirtz CraterPrimary · checked Oct 6, 2026
- ESA — Dark meets light on MarsPrimary · checked Oct 6, 2026
- NASA Photojournal — PIA19400: Sunset in Mars’ Gale CraterPrimary · checked Oct 6, 2026
- NASA JPL — NASA’s Curiosity Rover Views Serene Sundown on MarsPrimary · checked Oct 6, 2026
- Aerospace America (AIAA) — European Space Agency rethinks Mars plans as it kicks off a ‘mission-dense’ 2026Secondary · checked Oct 6, 2026
- House Appropriations Committee — Division A – Commerce, Justice, Science: Joint Explanatory Statement (MSR, p. 54)Primary · checked Oct 6, 2026