The Infrared Universe: Milky Way
The densely packed starfields at our galaxy's center are hidden behind dust clouds and only become visible in infrared light. In the near-infrared they begin to appear, but are reddened for much the same reason that sunlight turns red when filtered through a smoky cloud. The dense dust clouds begin to stand out at longer infrared wavelengths, taking on changing rainbows of color depending on which parts of the spectrum contribute to the image. The very coldest, densest dust will only start to glow at the very longest wavelengths of light, rendered in red in the far-infrared image in this sequence.
CREDITS: Far-infrared: ESA/NASA/JPL-Caltech. Mid-infrared: NASA/JPL-Caltech. Near-infrared: NASA/JPL-Caltech/S. Stolovy (Spitzer Science Center).