Images captured by NASA’s Curiosity rover have shown rare iridescent clouds drifting across the Martian sky. These formations, observed in the planet’s twilight, were seen at high altitudes where sunlight still reaches them despite nightfall on the surface. The images were taken on January 17, using one of the rover’s onboard cameras, with individual frames stitched together to create a time-lapse video. Scientists are analysing these cloud patterns to gain insights into Mars’ atmospheric processes and climate conditions.

Details of the Findings

A report from NASA’s Jet Propulsion Laboratory (JPL) detailed that these high-altitude clouds, composed of carbon dioxide ice, were seen floating between 60 and 80 kilometres above the surface. The cold temperatures at these heights cause the condensation of carbon dioxide, forming distinctive cloud structures. Some of the ice crystals were observed descending before evaporating at approximately 50 kilometres, where temperatures begin to rise.

As reported by space.com,that this is the fourth Martian year in which Curiosity has recorded these cloud formations. The phenomenon was first observed by NASA’s Pathfinder mission in 1997, which captured images from a location just north of the Martian equator.

Expert Analysis on Martian Clouds

In a statement to NASA’s JPL, Mark Lemmon, Atmospheric Scientist at the Space Science Institute in Colorado, remarked that the first sighting of these iridescent clouds was initially thought to be a colour anomaly. He highlighted that their seasonal recurrence has allowed researchers to predict their appearance and plan observations in advance.

Last year, scientists produced the most comprehensive cloud map of Mars, compiled from two decades of data gathered by the European Space Agency’s Mars Express orbiter. This study classified a range of cloud formations, including patterns not seen on Earth. Daniela Tirsch, Planetary Geologist at the German Aerospace Center, commented at the time that Martian clouds exhibit significant diversity.

Unanswered Questions About Cloud Formation

Observations have so far been limited to specific regions, with no twilight clouds detected by the Perseverance rover, which landed in Jezero Crater in 2021. This has led scientists to question what makes certain areas more conducive to their formation.

Lemmon explained that carbon dioxide was not expected to condense into ice at these altitudes, suggesting an unknown cooling mechanism at work. He pointed to atmospheric gravity waves as a possible factor, though their role in Martian weather patterns remains uncertain. Further studies are planned to better understand these cloud formations and their implications for the planet’s climate.