Westerhout 40 (W40) is a star-forming region in the Milky Way located in the constellation Serpens, approximately 1,420 light-years from the Solar System. This photograph, taken by NASA's Spitzer Space Telescope, reveals the stellar nursery in infrared light. A young cluster of several hundred stars is located at the center of the nebula, and stellar winds and radiation emanating from these stars have blown bubbles in the surrounding gas; the expanding bubbles have produced the rough shape of a butterfly seen in the image. Spitzer's Infrared Array Camera took this mid-infrared image in the 8.0-micron, 5.8-micron, 4.5-micron and 3.6-micron bands, here represented by red, orange, green and blue, respectively.Photograph credit: NASA/JPL-Caltech