Heavy Weather

Yes, snow was general all over London yesterday (that’s the view in my local park early in the afternoon, above), and for a little while everything more or less came to a stop.


On Titan, it may be raining right now, although at around minus 180 degrees Centigrade the rain is far colder than our snow. It’s liquid methane and ethane, and infrared pictures from Cassini showing the same area of Titan’s northern hemisphere in 2004 and 2005 have not only captured rainclouds, but also show one large lake expanding, and a whole cluster of smaller lakes appearing after what must have been a cloudbusting rainstorm. You can find a full report and links to the original pictures here. Before Cassini arrived at Saturn we had no idea what the surface of Titan looked like; now we’re beginning to understand the moon’s climatological cycles.

The past few months have been a jackpot as far as capturing extraterrestrial weather is concerned. The Phoenix lander spotted snow falling on Mars, while astronomers using the Spitzer telescope have detected changes in the infrared signature of planet HD 80606b, a superJupiter gas giant that orbits a star 190 light years from Earth. HD 80606b’s orbit is highly elliptical, and as it swings in close past its star it receives a huge heat pulse: the image below was generated by a computer model, showing a hurricane of supersonic winds heated to over 12000 degrees Centigrade racing towards the (blue) nightside of the gas giant. Which kind of puts our recent little weather event into perspective.