NASA’s Curiosity rover on Mars records spectacular natural phenomenon for first time

Mars is a dusty and cold desert world known for its red appearance, but did you know that the planet's clouds are iridescent?

New images captured by NASA’s Curiosity rover have given us Earthlings a glimpse into the colourful twilight clouds in the Martian sky.

The rover’s Mastcam, which are essentially the machine’s eyes according to NASA’s Jet Propulsion Laboratory. The clouds were spotted on 17 January and were taken over the course of 16 minutes.

Red and green tints can be spotted in the twilight clouds (also known as noctilucent) as they drift across the sky. Sometimes rainbow colours may be spotted in the clouds, according to a press release by NASA, producing iridescent or what is referred to as “mother-of-pearl” clouds. These colours are too faint to be seen in daylight and are only visible when the clouds are very high and during the evening.

NASA’s Curiosity Mars rover captures images of twilight clouds on MarsNASA/JPL-Caltech/MSSS/SSI

Why can we see colours in the clouds? They’re made up of frozen carbon dioxide, otherwise known as dry ice. When the Sun sets, its scattering light giving these clouds a stunning tint.

Although the Martian atmosphere is 95 per cent carbon dioxide, very few of the planet’s clouds are at a high enough atmosphere and low enough temperature to contain frozen CO2. Most clouds on Mars are made up of water ice. However the images taken by Curiosity are at an altitude of 37 to 50 miles above the planet’s surface. "They’re also visible as white plumes falling through the atmosphere, traveling as low as 31 miles (50 kilometers) above the surface before evaporating because of rising temperatures," the press release adds.

The first time Twilight clouds were spotted on the Red Planet by NASA’s Pathfinder mission in 1997. They’re a rare phenomenon that only happens in the early autumn in the southern hemisphere.

Mark Lemmon, an atmospheric scientist with the Space Science Institute in Boulder, Colorado, said: “I’ll always remember the first time I saw those iridescent clouds and was sure at first it was some colour artefact.

“Now it’s become so predictable that we can plan our shots in advance; the clouds show up at exactly the same time of year.”

NASA’s Perseverance Rover has spotted a lot of fascinating Martian oddities, including possible evidence of ancient life, but it has not seen the clouds since it landed in 2021. Curiosity, however, has seen them in four different Mars years.

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