There’s a great mystery unfolding on Mars, and NASA has detected a rare phenomenon that appears at the same time every year. With the help of the Curiosity rover, impressive images have been captured, showcasing the heavenly curiosities of the red planet. The Curiosity rover has seen some rare and beautiful twilight clouds on the planet, adding to the mystery. Noctilucent clouds, which shine at night, are typically seen on Earth during the summer months, but Curiosity has detected them on Mars as well.
These Martian clouds are composed of water or carbon dioxide, formed at higher altitudes where temperatures plummet. The carbon dioxide ice clouds, observed at heights between 60 and 80 kilometers, are the only ones known to produce iridescence. In newly published images, they appear as bright white columns that fall through the atmosphere before evaporating about 50 kilometers above the surface due to the increase in temperatures. Meanwhile, water ice clouds move in the opposite direction at a similar altitude, creating a dynamic atmospheric dance.
The Color Variation of the Clouds is Due to Light Dispersion, But There’s a Mystery
The phenomenon, which occurs when sunlight is dispersed through ice crystals, usually produces an amazing rainbow effect, forming iridescent or “nacreous” clouds. These clouds remain invisible during the day and only appear when twilight descends, staining the sky with ethereal tones. However, planetary scientists are left wondering why these clouds seem to appear only in certain regions of Mars. The first registered sightings of crepuscular clouds on Mars date back to NASA’s Pathfinder mission in 1997.
It wasn’t until 2019 that Curiosity captured its first images of iridescent clouds. Now, in its fourth Martian year of observations, the rover continues to provide valuable information about these fleeting atmospheric characteristics. Despite its predictability, there’s still a pending mystery: why do carbon dioxide twilight clouds have only been observed in certain regions of Mars? Curiosity, parked in Mount Sharp in the Gale crater near the equator, has provided the most extensive observations.
Cloud Formation on Mars and the Mystery Surrounding It
The noctilucent clouds on Mars are, like on Earth, too faint to be seen during the day and are only visible when the clouds are high and night has fallen. Mars clouds are formed by water ice and, at higher altitudes and lower temperatures, carbon dioxide ice. In fact, the Martian atmosphere is composed of more than 95% carbon dioxide. These high carbon dioxide clouds are the only ones that seem to produce such colorful iridescence on the red planet.
So, what causes the clouds to apparently only appear in certain places on Mars? Scientists believe that gravitational waves could be the reason. Although many mysteries still surround them, these findings help scientists rebuild the ancient environment of Mars, shedding light on whether the planet could or can ever house life. NASA’s Rover Perseverance in the Jezero crater, located in the northern hemisphere, has not yet detected similar clouds, leaving scientists to speculate about the role of gravity waves in their formation.