“This reveals the only known example of carbon-dioxide snow falling anywhere in our solar system,” NASA says.
Carbon dioxide freezes at minus 125 degrees Celsius.
The snowfalls occured from clouds around Mars’ South Pole in winter.
The data from the clouds was gathered by looking at them straight overhead and sideways with the “Mars Climate Sounder,” a device which measures 9 bands of visible and infrared light.
It identified a tall carbon-dioxide cloud about 300 miles (500 kilometers) in diameter persisting over the pole and smaller, shorter-lived, lower-altitude carbon dioxide ice clouds at latitudes from 70 to 80 degrees south.