Not only are these clouds at higher altitudes than usual, but they show off a beautiful palette of colors in the Martian sky.
Cloudy days are rare on Mars. It has to do with its thin, dry atmosphere. We therefore only see clouds during the coldest time of the year on the equator, when Mars is furthest from the sun. But a year ago on Mars – two years ago on Earth – the Martian rover Curiosity suddenly spotted clumps of clouds earlier than expected. Scientists therefore decided to go there at the beginning of the year to study the phenomenon more closely.
The Martian rover Curiosity once again kept its keen eyes on the sky. And indeed, the mysterious “first clouds” also appeared earlier than expected this year. They first appeared at the end of January. Curiosity captured the dramatic cloud cover in several photos. Such images are therefore more than just spectacular photos; they help scientists understand how clouds form on Mars. Additionally, scientists now have a better understanding of how these recently observed cloud sails differ from “normal” Martian clouds.
First, the researchers find that these early clouds are at higher than normal altitudes. Most of the clouds on Mars do not float more than 60 kilometers above the Martian surface and are made up of water ice. But the clouds photographed by Curiosity are much higher, in the colder regions. This means that the clouds are probably not water ice, but frozen carbon dioxide or dry ice.
The fine, undulating textures of these clouds are clearly visible in the photos taken with Curiosity’s black and white navigation cameras:
But in the images below, the clouds really seem to be twinkling. Literally. Just after sunset, the ice crystals in the clouds reflect the fading light, making them stand out strongly against the darkening sky.
Even more astonishing are the iridescent or “pearl” clouds, seen below. Beautiful swirls of clouds fill the Martian sky.
How do they arise? “If you see a cloud with a shimmering pastel color, it’s because the particles in the cloud are all the same,” says researcher Mark Lemmon. “It usually happens right after the clouds have formed and they all ‘grow’ at the same rate. These clouds are one of the most colorful phenomena on the vast and monotonous red planet. “If you looked at the sky next to Curiosity, you could see the colors – probably a little blurry – with the naked eye,” Lemmon says.
Thanks to these beautiful clouds, we get a better idea of the phenomena in the atmosphere of the red planet. And apparently Mars is less gray and monotonous than you might think. Clouds filled with ice crystals diffuse the light of the setting sun, making them glow in the sky in different beautiful colors. “I am amazed by the colors that appear: red, green, blue and purple,” says Lemmon. “It’s really cool to see something shining in many colors on Mars.”