When astronomers want to com- pare several images of the same object made at different wavelengths of light, they often construct composite images. In this image of Maffei 2, three wavelengths, all normally invisible, have been combined into a single false color image. Infrared light is red, radio light is green, and hydrogen gas at radio wavelengths is blue. The galaxyΓÇÖs nucleus appears bright yellow. Color theory tells us that yellow is a comb- ination of red and green, so we can surmise that there is strong infrared and radio emission from the nucleus, but no hydrogen gas. The whitish areas are regions where all three emissions are present (white is a combination of red, green, and blue).
