NASA researchers, utilizing the Curiosity rover, have shifted focus from merely examining the Martian surface to investigating atmospheric phenomena. Their interest is particularly piqued during periods when Mars is at its farthest distance from the Sun.
During these times, the equatorial region of Mars experiences a season of cloudy days, coinciding with the planet's coldest season. Notably, a Martian year spans approximately two Earth years, totaling 687 Earth days. Cloudy days on Mars are infrequent, with clouds appearing as thin layers within the planet's arid atmosphere.
Since 2021, NASA scientists have observed that clouds over Mars have been forming earlier than usual. The Curiosity rover began capturing images of these clouds in January 2021, providing valuable data that aids researchers in determining cloud formation processes, structures, and characteristics.
Through their studies, scientists discovered that these early clouds form at altitudes exceeding 60 kilometers above the planet's surface and are likely composed of frozen carbon dioxide. Additionally, Martian clouds exhibit a finer structure compared to terrestrial clouds.
There are two types of clouds identified: traditional clouds that form at altitudes up to 60 kilometers, composed of water ice, and a second type that forms above this altitude, consisting of carbon dioxide or potentially dry ice.
Observations made after sunset have enabled scientists to more accurately ascertain the height of these clouds. As the sun sets below the horizon, ice crystals within the clouds become more pronounced and luminous, gradually darkening as the sun's position falls below their altitude.
The wavy structure of the clouds is more easily discerned in black-and-white images captured by the rover's navigation cameras (NavCam and MastCam). In contrast, color images from the rover's mast camera reveal sparkling clouds in the Martian sky, which appear to literally shine.
Meteorologist Mark Lemmon, affiliated with the Space Science Institute in Boulder, Colorado, reports that these sparkling clouds rank among the brightest features on the Red Planet.
'If we were on Mars and looked up at the sky, we would see the entire spectrum of colors in the clouds with the naked eye,' Lemmon stated.
Due to its thin atmosphere, Mars experiences extreme temperature fluctuations. During summer, temperatures can rise to +20 degrees Celsius, with a maximum recorded temperature of +35 degrees. Conversely, nighttime temperatures can plummet to -80 degrees, and winter temperatures can reach as low as -140 degrees.