Comet C/2006 W3 Christensen, NEOWISE image. This Oort cloud comet was discovered on 18 November 2006 by E. J. Christensen (Catalina Sky Survey). Comets are icy bodies from the outer solar system that boil and form a bright tail of gas and dust as they approach the Sun. Here, the imaging technique and the comet's dust thermal emission, produces this golden colour. This image was obtained in infrared by NASA's NEOWISE (Near-Earth Object Wide-field Survey Explorer) on 20 April 2010.