Two extremely bright stars illuminate a greenish mist in this and other images from the new GLIMPSE360 survey from NASAs Spitzer Space Telescope. This fog is comprised of hydrogen and carbon compounds called polycyclic aromatic hydrocarbons (PAHs), which are found right here on Earth in sooty vehicle exhaust and on charred grills. In space, PAHs form in the dark clouds that give rise to stars. These molecules provide astronomers a way to visualize the peripheries of gas clouds and study their structures in great detail. They are not actually green; but are colour coded in these images to let scientists see their glow in infrared.