Here’s another cool image from Cassini, showing sunlight glinting off the surface of a lake in Titan’s northern hemisphere.
Cassini’s radar has been mapping the lakes for the past couple of years, and we’ve been quite confident in calling them lakes because their smoothness and high reflectivity to radio waves indicate that they are indeed filled with what are probably liquid hydrocarbons. Somehow, though, a picture like this makes it seem more real. True, this ‘eyeball confirmation’ comes in the form of a heavily processed image taken at infrared wavelengths; but it still impresses me.
This is the first time since Cassini reached Saturn that a picture like this would have been possible – Titan’s nothern hemisphere is just emerging from its winter, exposing the lakes to sunlight for the first time in about 15 years. It will be interesting to see what effect the change of seasons may have on them – current thinking seems to be that they will shrink by evaporation, whilst a rainy winter in the (presently drier) southern hemisphere will lead to the growth of new lakes there. Hopefully Cassini will survive long enough too see whether this is the case or not.