Near-infrared image of Uranus ring system taken with the Adaptive Optics system on the 10-m Keck telescope in July 2004. This image, taken at 2.2 micron wavelength, shows the main ring system in reflected sunlight. This particular wavelength was chosen since Uranus itself is dark, since methane gas in its atmosphere absorbs most of the incoming sunlight, so that the relatively faint rings do stand out. In between the main rings, which are composed of cm-sized or larger-sized particles, sheets of dust can be discerned.
Imke de Pater, Seran Gibbard and Heidi Hammel, Icarus 180, 186-200 (2006)