While the northern hemisphere of Earth experiences the winter solstice this week, there are also snowy winter scenes to be found on Mars. With average temperatures around minus 80 degrees Fahrenheit and dropping as low as minus 220 degrees Fahrenheit, Mars is a chilly place generally and is particularly so around the poles and during the winter. NASA recently shared a selection of photographs of Mars taken from orbit which show the winter weather to be found on our neighboring planet.
Weather on Mars is quite different from that on Earth because its atmosphere is so thin. At just 1% of the density of Earth’s atmosphere, the biggest weather events are not rainstorms but dust storms, as dust is whipped up from the surface into large storms which 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 is so cold.
“Enough falls that you could snowshoe across it,” said Sylvain Piqueux, a Mars scientist at NASA’s Jet Propulsion Laboratory, in a statement. “If you were looking for skiing, though, you’d have to go into a crater or cliffside, where snow could build up on a sloped surface.”
This image, taken by the Mars Reconnaissance Orbiter’s HiRISE instrument, shows dry ice forming frost over sand dunes in the martian winter. A fun fact about dry ice snowflakes is that, unlike water ice snowflakes which always have six sides, carbon dioxide snowflakes would be a different shape.
“Because carbon dioxide ice has a symmetry of four, we know dry-ice snowflakes would be cube-shaped,” Piqueux said. “Thanks to the Mars Climate Sounder, we can tell these snowflakes would be smaller than the width of a human hair.”
The Mars Climate Sounder is another of the Mars Reconnaissance Orbiter’s instruments, which looks in the infrared wavelength to peer through clouds and see details about the martian climate.
In addition to orbiters, we are also learning about martian weather using instruments on the ground, such as the Perseverance rover’s MEDA suite which can measure wind speed and direction, pressure, and temperature from its location in the Jezero Crater.
You can see even more images of winter on Mars by heading over to NASA JPL’s website.
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