Image Credit: Mike Brown
Mike Brown, the discoverer of Pluto-killing Eris, has discovered fog on Titan. This is an amazing discovery as it implies there are large quantities of liquid methane on Titans surface. We have long suspected this (and a lot of the dark patches on Titan are suspected to be methane lakes), but confirmation is pretty stunning.
Read Mike's blog for the details (Mike Brown has a Blog! It's going in my Blog Roll!), and links to his paper. (Hat tip to the Bad Asytomomer, whose own post on this should be read attentively too.)