NASA’s Curiosity rover has captured 16 minutes of footage showing colorful, rainbow-hued clouds on Mars. The Martian twilight clouds, also known as noctilucent clouds, are too faint to see in daylight and appear iridescent when light from the setting sun hits them. Scientists released a sped-up video of the clouds, which show red and green hues.
Unlike Earth’s water-ice clouds, Mars’ mother-of-pearl clouds are made of dry ice and don’t exist in the Martian atmosphere due to lack of water vapor at high altitudes. Curiosity’s left Mastcam camera captured the images near the top of the frame at an altitude of 37-50 miles.
The noctilucent clouds form when ice crystals condense on meteor smoke, a process that was studied by NASA’s Aeronomy of Ice in the Mesosphere mission. Researchers learned that these clouds are a single continuous layer and shimmer at dusk and dawn near Earth’s poles.
Curiosity’s observations are the fourth year it has spotted these clouds in the early fall, but the reason for their rarity on other parts of Mars is still unknown. Scientists speculate that gravity waves might be causing carbon dioxide to condense into ice in southern latitudes.
The discovery of Martian twilight clouds surprises scientists every time they see new examples, and NASA’s Curiosity rover has made significant contributions to understanding these rare atmospheric phenomena.
Source: https://mashable.com/article/mars-curiosity-rover-noctilucent-rainbow-clouds