Figure 3-40 Survey of the Universe in Various Parts of the Electromagnetic Spectrum By mapping the celestial sphere onto a flat surface (like making a map of Earth), astronomers can see the overall distribution of strong or nearby energy sources in space. The center of our Galaxy’s disk cuts these images horizontally in half. Because most of the emissions shown in these images fall in this region, we know that most of the strong sources of various electromagnetic radiation as seen from Earth (except X-rays) are in our Galaxy: (a) radio waves, (b) infrared radiation, (c) visible light, (d) X-rays, and (e) gamma rays.