Polar vortex: winter is coming to Titan, as the southern latitudes of Saturn’s largest moon begins to move into darkness. In this true color image from June 27th, NASA’s Cassini spacecraft spots a swirling mass of gasses in Titan’s atmosphere over its southern pole. This may be a sign of open cell convection taking place, though it’s hard to say without being able to peer under the highest clouds visible (image credit: NASA/JPL-CalTech/Space Science Institute).