Fractal Interstellar Dust Up Close

Our universe is a very dusty place. Dust usually shows its presence by blocking out light emitted from stars or nebulae behind it, sometimes creating the illusion of a horse's head or a sombrero hat . But nobody really knows what a typical interstellar dust grain looks like. By studying how dust absorbs , emits , and reflects light, astronomers do know that interstellar dust is much different than the cell and lint based dust found around a typical house . Interstellar dust grains are composed mostly of carbon , silicon , and oxygen and are usually less than about 1/1000 of a millimeter across. Recent work indicates that most dust grains are not spherical . The above picture shows the result of a fractal adhesion model for dust grains involving random conglomerates of spherical compounds of different properties, here artificially highlighted by different colors.