Mars is often thought of as a barren wasteland, but its skies reveal a stunning beauty. Unlike Earth’s clouds, which are made of water vapor, Martian clouds are composed of frozen carbon dioxide, also known as dry ice.
These clouds can appear in vibrant red and green hues, creating a spectacular sight that captivates scientists. Recently, NASA’s Curiosity rover captured stunning images of these clouds drifting across the Martian sky. The photographs were taken over 16 minutes on January 17, 2025, showcasing a fascinating atmospheric event.
These clouds are called noctilucent or “night shining” clouds because they glow in the fading light of the sun. This twilight effect sometimes creates a rainbow-like display known as iridescence. The ongoing study of these clouds helps scientists learn more about the atmosphere and weather patterns on Mars.
Cloud formation on Mars occurs under extreme conditions. Mars hosts two types of clouds: water ice clouds, which generally form at lower altitudes, and carbon dioxide ice clouds that appear much higher, where temperatures plummet. Interestingly, dry ice clouds are the only ones on Mars known to show iridescence, resulting from sunlight scattering through tiny particles.
Curiosity’s latest captures show these clouds floating between 37 and 50 miles (60 to 80 kilometers) above the surface. Some of these clouds drop to 31 miles (50 kilometers) before evaporating due to rising temperatures, while other water-ice clouds hover around that altitude, forming and dissipating as atmospheric conditions change. The contrasting movement of these two types of clouds adds complexity to Martian weather.
Although twilight clouds were first spotted by NASA’s Pathfinder mission in 1997, Curiosity only observed them in 2019. Over four Martian years, the Curiosity rover has documented how these unique clouds appear at the start of fall in Mars’s southern hemisphere, providing fresh insights into their behavior.
Mark Lemmon, an atmospheric scientist at the Space Science Institute, remarked on the predictability of these clouds. This consistency allows scientists to plan their observations better. Each image recorded by Curiosity builds a clearer picture of cloud formation on Mars, helping researchers analyze the size and growth rates of cloud particles.
Despite much observation, scientists are still puzzled by one lingering question: why do carbon dioxide clouds form in certain regions of Mars but not in others? Curiosity, operating in Gale Crater near Mars’s equator, has frequently captured these clouds, while the Perseverance rover hasn’t recorded any since its arrival in Jezero Crater in 2021.
Some theories suggest that specific areas may create conditions that are more conducive for cloud formation, possibly involving gravity waves that cool the atmosphere enough for carbon dioxide to freeze into ice. However, these processes remain poorly understood.
Curiosity’s images offer a unique look at the Martian atmosphere. One camera, the Mastcam, has been capturing the clouds even though a malfunction has limited its field of view. Yet, the rover’s other Mastcam has taken higher-resolution images, further aiding in the study of Martian weather.
Curiosity’s mission is not solely focused on clouds. It is also investigating Mars’s geological history. For instance, the rover recently explored “Rustic Canyon,” a small crater that has weathered over millions of years. Studying impact craters like this one can reveal ancient materials that may hint at the planet’s past conditions.
As Curiosity continues its journey, the insights gained from these observations of clouds and geological features bring us closer to understanding the Red Planet’s climate and its potential for hosting life.
