Red, White, and Blue Comet

Today is the Fourth of July, Independence Day in the States. By a charming coincidence, an image was released today of a comet passing the Earth, and it happens to be red, white, and blue! That is comet C/2012 K1 (Pan-STARRS), which is currently sweeping around the Sun. The image is actually a composite of several observations taken over a few hours on May 20, 2014. The observations are from NASA's Wide-field Infrared Survey Explorer, or WISE. The camera detects infrared light -- in this picture...