The galatic image at a wavelaength of 21 cm (in the radio part of the spectrum),show where warm and cool interstellar gas in found(Figure 22.3).Like the dust,the warm and cool interstellar gas is concentrated in a thin band. At other radio wavelengths(Figure 22.4)we see mainly synchrotron emission from rapidly moving electrons.Tongues of emission extend far above and below the thin band of the Milky Way. The hottest gas in the galaxy emits X-rays. The X-rays image of the galaxy in Figure 22.5 shows X-rays emission from all directions.