The Telescope Its History, Technology, and Future

About this book

In the four centuries since its invention, the telescope has transformed how humans view the universe and their place in it. But what do most of us know about telescopes themselves--their history, how they work, what they are being used for today, or what the next generation of billion-dollar telescopes will look like? In The Telescope, Geoff Andersen fills in all the details for us in an accessible, nontechnical way that will appeal to the amateur astronomer and anyone else who has been more than a little curious about this amazing instrument.

The book covers every aspect of optical telescopes - from the humblest backyard setup, to state-of-the-art observatories, to the Hubble Space Telescope and spy satellites. Chapters describe the development, design, and operation of telescopes; how observatories are sited, engineered, and built; variations such as solar and liquid-mirror telescopes; and some of the key astronomical discoveries telescopes have made possible. And there are plenty of surprises along the way. We learn, for example, that most of today's professional astronomers never even look through their own telescopes, relying instead on digital imaging, measurement, and analysis - or even remote computer control of a night-shrouded observatory on the other side of the Earth.

But, as this book explains, these magnificent instruments do more than simply peer into space. They project and receive laser beams - for communicating, mapping, and making detailed observations of the Earth. They also look down at us from spy satellites, providing secret images to intelligence agencies - and, increasingly, giving a curious public access to more pedestrian images.

Contents

Preface 9 Chapter 1: The naked-eye universe 13 Chapter 2: The development of the telescope 25 Chapter 3: How a telescope works 37 Imaging Refracting telescopes Reflecting telescopes Chapter 4: The perfect telescope 44 Diffraction and the perfect image Resolution limit Chapter 5: When good telescopes go bad 53 Aberrations Field of view Air turbulence Chapter 6: Analysing the light 66 Imaging devices--the camera Spectroscopy Photometry Polarimetry Chapter 7: Interferometry 80 Interference--how light waves combine Michelson interferometer Michelson stellar interferometer Imaging interferometry Nulling interferometry Chapter 8: So you want to build an observatory? 95 Making a mirror Site selection Mechanical engineering Chapter 9: The Hubble Space Telescope 109 Chapter 10: Advanced telescope techniques 125 Lightweighting Active optics Segmented primaries Adaptive optics Laser guide stars Chapter 11: Laser communications and remote sensing 140 Laser communications Lidar Chapter 12: Surveillance 149 Airborne surveillance Space-based surveillance Other surveillance methods Laser weapons Chapter 13: Non-traditional observatories 162 Liquid mirror telescopes Solar telescopes Seeing the invisible Gravitational wave observatories Chapter 14: Key discoveries 181 The Solar System and Pluto Comet Halley The first exo-solar planet Milky Way black hole Hubble Ultra-Deep Field Hoag's Object Chapter 15: Future telescopes 197 Wide-field wonders Another pale blue dot The big boys One last word 217 Appendix A: Some mathematical basics 220 Appendix B: Electromagnetic radiation 226 Appendix C: Getting your own telescope 233 Notes 236 Bibliography 240 Index 243

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Biography

Geoff Andersen is a research physicist at the United States Air Force Academy, where he studies telescope and microscope design, holography, and remote sensing. He has worked on projects funded by the U.S. Air Force and NASA.