Scientists confirm 'dry ice' snowfall on Mars

In 2008, we learned from the Phoenix Mars lander that it snows in the Martian north polar region — perhaps quite regularly — from clouds made of water vapor. But now, Mars Reconnaissance Orbiter data has revealed the clearest evidence yet of carbon-dioxide snowfalls on Mars. Scientists say this is the only known… »9/12/12 2:20pm9/12/12 2:20pm