ABSTRACT
In Chapter 1 I explained that the range of frequencies in the electromagnetic spectrum spans some 23 octaves, of which we directly perceive less than a single octave. But every part of this vast spectrum is capable of conveying information in the form of images. We have now looked in detail at the methods of recording the visible part. In the case of astronomy, we have gone further, into the realms of cosmic radiation covering the whole electromagnetic spectrum. It is time to look at the way we capture and use images from the invisible radiation we find within the living world.
