Space dust enigma
The pinwheel galaxy, also known as Messier 101, sports bright reddish edges in this infrared image from NASA’s Spitzer Space Telescope. Research based on Spitzer data has revealed that this outer red zone lacks organic molecules present in the rest of the galaxy. The red-and-blue spots outside of the spiral are either foreground stars or more distant galaxies. The organics, called polyclinic aromatic hydrocarbons, are dusty, carbon-containing molecules that help form stars. scientists found that the polyclinic aromatic hydrocarbons decrease in concentration toward the outer portion of the Pinwheel galaxy, then quickly drop off and are no longer detected at its outer rim. According to astronomers, there is a threshold at the rim where the organic material is being destroyed by harsh radiation from
