Galactic centre, infrared Spitzer Space Telescope image. This region at the centre of our Milky Way galaxy is invisible at optical wavelengths because of the large amount of obscuring dust. Infrared radiation can penetrate the dust, however, allowing the hundreds of thousands of stars there to be seen. The white dot at centre is the very centre of the Milky Way, which houses a supermassive black hole. In this image, older, cooler stars are blue, while hot, massive stars are red. Many dark dust clouds are seen. The image spans 890 by 640 light years. Different wavelengths are colour-coded: 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8 microns (red).