Spying Titan's weather

These false-colour images of Titan were obtained by the Cassini-Huygens Visual Infrared Mapping Spectrometer during the 26 October/13 December Titan fly-bys, from distances of between 200 000 and 225 000 kilometres.

The colours red, green and blue represent near-infrared images obtained at 2.01 micron, 2.83 micron and 2.13 micron, respectively. These colours explore the surface and atmosphere of Titan with varying effectiveness. The red images the surface at a wavelength (2.01 micron) where the surface is relatively bright, making the surface appear reddish in these colour images. The green colour (2.83 micron) images the surface as well, but due to enhanced absorption of sunlight by the surface and lower atmosphere, the surface is relatively dark here compared to the red. The blue colour (2.13 micron) is at a wavelength where sunlight cannot reach the surface at all due to strong absorption by the atmospheric gas methane.

In contrast to the reddish surface, bright clouds at a relatively high altitude (here, about 30 kilometres above the ground) residing above most of the atmospheric absorption appear whitish in these representations, as they reflect sunlight effectively in all three near-infrared colours.