While the winter solstice takes place in the northern hemisphere of the earth this week, there are also snowy winter scenes on Mars. With average temperatures averaging around minus 80 degrees Fahrenheit and a low of minus 220 degrees Fahrenheit, Mars is generally a cool place, especially near the poles and in winter. NASA recently shared a selection of photos of Mars from orbit showing winter weather on our neighboring planet.
The weather on Mars is very different than on Earth because its atmosphere is so thin. At only 1% the density of the Earth’s atmosphere, the biggest weather events are not rainstorms but dust storms, as dust from the surface is blown up into large storms that can cover the entire planet. However, there is occasional snow on Mars, and it comes in two forms: water ice snow, like we have on Earth, and carbon dioxide, or dry ice snow, which forms because it’s so cold.
“Enough falls to cross on snowshoes,” Sylvain Piqueux, a Mars scientist at NASA’s Jet Propulsion Laboratory, said in a statement. “However, if you wanted to ski, you would have to go into a crater or cliff where snow could accumulate on a sloped surface.”
This image, taken by the Mars Reconnaissance Orbiter’s HiRISE instrument, shows dry ice forming frost over sand dunes during the Martian winter. A fun fact about dry ice snowflakes is that unlike water ice snowflakes, which always have six sides, the carbon dioxide snowflakes have a different shape.
“Because carbon dioxide ice has a symmetry of four, we know that dry ice snowflakes would be cube-shaped,” Piqueux said. “Thanks to the Mars Climate Sounder, we can say that these snowflakes are smaller than the width of a human hair.”
The Mars Climate Sounder is another Mars Reconnaissance Orbiter instrument that uses infrared to see through clouds and see details about the Martian climate.
In addition to orbiters, we’re also learning about Martian weather using ground-based instruments like the Perseverance rover’s MEDA suite, which can measure wind speed and direction, pressure and temperature from their location in Jezero Crater.
You can see more images of winter on Mars by going to NASA’s JPL website.