Snowfall on Mars

Dry ice to be be specific

NASA's Mars Reconnaissance Orbiter (MRO) has returned the first definitive evidence of carbon dioxide snowfalls on Mars - the only place this is known to happen anywhere in our solar system.

Frozen carbon dioxide - better known as 'dry ice' - requires a temperature of about minus 193 degrees Fahrenheit. The snow was seen falling around Mars's south pole in winter.