Dense dust in galactic plane, infrared image. The clouds of dust (black) at centre are themselves part of larger gas and dust clouds (nebulae) in the plane of the Milky Way galaxy. These clumps of dust have been found to be extremely dense, throwing deep shadows on their surroundings in both visible and infrared light (dust clouds are normally transparent to the latter). It is thought the dust clouds will evolve into a massive cluster of hot, young O-type stars. Image data obtained by the IRAC (infrared array camera) and MIPS (multiband imaging photometer for Spitzer) sensors on NASA's Spitzer Space Telescope (SST). Image published in 2014.