Serge Brunier is an awardwinning science journalist and author of the best-selling The Great Atlas of the Stars.

Anne-Marie Lagrange is a prominent astrophysicist associated with the Observatoire de Grenoble, France.

Catherine Césarsky is the Director General of the European Southern Observatory.

This book is a collaborative effort between an award-winning science journalist and a widely recognized professional astrophysicist, and provides a unique overview of both contemporary world observatories and of telescopes in the future.

Thanks to remarkable advances in optics and electronics, astronomers have made impressive new discoveries in recent decades. Moreover, they no longer have to spend long, uncomfortable nights in the dead of winter in observing cages on top of their telescopes, or with their eyes glued to a dimly lit eyepiece reticle following a guide star. During the 1970s, they began observing in the comfort of heated rooms, and controlling their telescopes, support instrumentation and images with computers.

In due course, electronic detectors with far greater sensitivity and better contrast replaced the photographic plate. Radio astronomy also made impressive advances, including pioneering the use of aperture synthesis and interferometry, which greatly increased image resolution and quality. Space-based astronomy was the next great stride forward; by rising above the Earth's atmosphere, astronomers were no longer limited to the visible end of the spectrum, but now observed at wavelengths that included ultraviolet, X-ray and gamma-ray emissions. This helped reveal a far more violent cosmos than hitherto imagined, by showing a universe filled with incredible explosions and energy, and with black holes devouring everything in their reach.

Sadly, one of the great ironies of the 20th century is that while astronomers can now probe the universe at all possible wavelengths, from Earth as well as from space, ever-increasing light pollution has progressively rendered the night sky less and less accessible to the average citizen.

In their quest for ever-sharper celestial images, Earth-based astronomers and observatories have long been hampered by such factors as instrument flexure, wind and atmospheric turbulence. To overcome this, they have developed flexible, computer-controlled optics that compensate for and correct such problems automatically. In fact, with the advent of active and adaptive optics, ground-based telescopes can now compete effectively with much costlier space-based instruments like the Hubble Space Telescope. As we begin the 2lst century, researchers have fully integrated ground and space-based instrumentation to maximize their effectiveness and to plan future projects. Collectively, this is leading to the establishment of a "virtual observatory," a huge repository of data and information accessible to the worldwide astronomical community, as well as to members of the general public who are interested in the findings of the great observatories.

In the United States, foundations and private donations have helped finance the most ambitious ground-based telescopes (including the twin Keck instruments in Hawaii), while in space, the most important projects have been funded by NASA. In Europe, intergovernmental collaborations among nations have helped make the largest projects possible. In space, although the European Space Agency (ESA) cannot match NASA's budgets, it has launched several successful missions, including Giotto, the first probe to a comet; Hipparcus, the first astrometric space observatory; and ISO, the first infrared space telescope. The latter also played a major role in collaboration with the SOHO solar mission. With establishment of the ESO at Cerro Paranal and a remarkable degree of collaboration, Europe has taken the lead in ground-based astronomy. Shared expertise among several national observatories led to the interferometers at Calern and Cambridge, research on exoplanets at Haute-Provence and La! Silla observatories, use of artificial stars for adaptive optics at Calar Alto, and so on. After their success with active and adaptive optics through the New Technology Telescope (NTT) and Adonis, as well as the deployment of the Very Large Telescope (VLT) and the Very Large Telescope Interferometer (VLTI), European astronomers are proposing the construction of an Overwhelmingly Large Telescope: the 100 m OWL.

In November 2003, a groundbreaking ceremony was held for a joint European and North American project: ALMA, a giant millimeter and submillimeter interferometer located in Chile at an elevation of 5,100 m on a vast plateau in the Atacama Desert. This project, which includes a number of other international partners, is the first example of scientific collaboration of this nature. It is perhaps fitting that astronomers, who are attempting to decipher the whole universe, should be the first to undertake a project of such truly global proportions.

However, our readers can rest assured that despite the daunting technological advances described in this book, professional astronomers are just as overwhelmed as they are by the great beauty and mysteries of the cosmos.

Foreword

This book is a collaborative effort between an award-winning science journalist and a widely recognized professional astrophysicist, and provides a unique overview of both contemporary world observatories and of telescopes in the future.

Thanks to remarkable advances in optics and electronics, astronomers have made impressive new discoveries in recent decades. Moreover, they no longer have to spend long, uncomfortable nights in the dead of winter in observing cages on top of their telescopes, or with their eyes glued to a dimly lit eyepiece reticle following a guide star. During the 1970s, they began observing in the comfort of heated rooms, and controlling their telescopes, support instrumentation and images with computers.

In due course, electronic detectors with far greater sensitivity and better contrast replaced the photographic plate. Radio astronomy also made impressive advances, including pioneering the use of aperture synthesis and interferometry, which greatly increased image resolution and quality. Space-based astronomy was the next great stride forward; by rising above the Earth's atmosphere, astronomers were no longer limited to the visible end of the spectrum, but now observed at wavelengths that included ultraviolet, X-ray and gamma-ray emissions. This helped reveal a far more violent cosmos than hitherto imagined, by showing a universe filled with incredible explosions and energy, and with black holes devouring everything in their reach.

Sadly, one of the great ironies of the 20th century is that while astronomers can now probe the universe at all possible wavelengths, from Earth as well as from space, ever-increasing light pollution has progressively rendered the night sky less and less accessible to the average citizen.

In their quest for ever-sharper celestial images, Earth-based astronomers and observatories have long been hampered by such factors as instrument flexure, wind and atmospheric turbulence. To overcome this, they have developed flexible, computer-controlled optics that compensate for and correct such problems automatically. In fact, with the advent of active and adaptive optics, ground-based telescopes can now compete effectively with much costlier space-based instruments like the Hubble Space Telescope. As we begin the 2lst century, researchers have fully integrated ground and space-based instrumentation to maximize their effectiveness and to plan future projects. Collectively, this is leading to the establishment of a "virtual observatory," a huge repository of data and information accessible to the worldwide astronomical community, as well as to members of the general public who are interested in the findings of the great observatories.

In the United States, foundations and private donations have helped finance the most ambitious ground-based telescopes (including the twin Keck instruments in Hawaii), while in space, the most important projects have been funded by NASA. In Europe, intergovernmental collaborations among nations have helped make the largest projects possible. In space, although the European Space Agency (ESA) cannot match NASA's budgets, it has launched several successful missions, including Giotto, the first probe to a comet; Hipparcus, the first astrometric space observatory; and ISO, the first infrared space telescope. The latter also played a major role in collaboration with the SOHO solar mission. With establishment of the ESO at Cerro Paranal and a remarkable degree of collaboration, Europe has taken the lead in ground-based astronomy. Shared expertise among several national observatories led to the interferometers at Calern and Cambridge, research on exoplanets at Haute-Provence and La Silla observatories, use of artificial stars for adaptive optics at Calar Alto, and so on. After their success with active and adaptive optics through the New Technology Telescope (NTT) and Adonis, as well as the deployment of the Very Large Telescope (VLT) and the Very Large Telescope Interferometer (VLTI), European astronomers are proposing the construction of an Overwhelmingly Large Telescope: the 100 m OWL.

In November 2003, a groundbreaking ceremony was held for a joint European and North American project: ALMA, a giant millimeter and submillimeter interferometer located in Chile at an elevation of 5,100 m on a vast plateau in the Atacama Desert. This project, which includes a number of other international partners, is the first example of scientific collaboration of this nature. It is perhaps fitting that astronomers, who are attempting to decipher the whole universe, should be the first to undertake a project of such truly global proportions.

However, our readers can rest assured that despite the daunting technological advances described in this book, professional astronomers are just as overwhelmed as they are by the great beauty and mysteries of the cosmos.