They see clouds dyed red and green. They move through the Martian sky in a new set of images captured by NASA’s Curiosity Rover. To find the colored clouds on Mars, he used his mastcam, his main set of “eyes.”
The images were taken for 16 minutes on January 17. They show the latest observations of what are called night clouds (from the Latin “bright night”), or twilight clouds. They are dyed color by the dispersed light of the west sun.
Nácar clouds
Sometimes, these clouds even create a colored rainbow, producing iridescent or “pearly” clouds. They are too faint to be seen in daylight. They are only visible when the clouds are especially high and the afternoon has fallen.
Martian clouds are made of water ice. Also, at higher altitudes and lower temperatures, carbon dioxide ice. The atmosphere of Mars is composed of more than 95% by carbon dioxide. The latter are the only clouds observed in Mars that produce iridescence. They can be seen near the top of the new images at an altitude of between 60 and 80 kilometers.
They are also visible as white columns that fall through the atmosphere. They travel up to 50 kilometers above the surface before evaporating due to the increase in temperatures. Clouds of water from water appear briefly at the bottom of the images. These travel in the opposite direction approximately 50 kilometers above the rover.
Marciano autumn
The twilight clouds were seen for the first time on Mars by NASA’s pathfinder mission in 1997. Curiosity did not detect them until 2019, when he acquired his first images of iridescence in the clouds. This is the fourth year on Mars in which the Rover observes the phenomenon. Colored clouds on Mars appear at the beginning of autumn in the southern hemisphere.
Mark Lemmon is an atmospheric scientist at Space Science Institute in Boulder, Colorado. He directed an article that summarizes the first two seasons of Curiosity Twilight Observations, published at the end of last year in Geophysical Research Letters.
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