It's beginning to look a lot like Christmas; Snow in Mars' Atmosphere
In The Guardian, Ian Sample has a very nice article
about how baby steps of exploration and scientific inquiry are making
subtle, gigantic changes to our understanding of our place in the
Universe. Just finding the snow crystals forming in the upper
atmosphere, for example – something that happens every day on Earth –
precipitates a gigantic change in our understanding of Mars. That
gigantic change in understanding is the result of decades of exploring
Mars with robots and telescopes. That change is that Mars is not a
barren, dry, dead planet.
There are some interesting ideas presented in the paper about the evolution of Mars as a planet.