A report being published in Journal of Geophysical Research confirms the evidence of “snow clouds” made of carbon dioxide that resolve into a “dry ice snowfall” at the Martian southern polar cap. An instrument on NASA’s Mars Reconnaissance Orbiter is able to examine atmospheric gases and particles by measuring brightness in visible and infrared light. Based on the data, the carbon dioxide clouds contain particles that are heavy enough to fall to the ground as snow. Also, the signature of the clouds extends to the surface, implying that snowfall may likely be taking place.
Subscribe for counterintuitive, surprising, and impactful stories delivered to your inbox every Thursday
What’s the Big Idea?
This is the only known carbon dioxide snowfall in the solar system, according to the report, and the southern polar cap is the only place on Mars where dry ice exists year-round on the surface. Prior to this, scientists only knew of the existence of ice as well as a kind of sleet in Mars’ northern hemisphere. Because carbon dioxide freezes at -193 degrees Fahrenheit, the possible existence of snow “reminds scientists that although some parts of Mars may look quite Earth-like, the Red Planet is very different.”