The search for other planetary systems: Progress to date and future prospects

Most of the truly fundamental questions in science involve the concept of "origins' in one way or another. Progress on experimental, observational and theoretical grounds over the past few decades, have led to the development of a paradigm for the origin of the solar system. The significance of this paradigm is that it links inextricably the formation of stars and the existence of planetary systems; it makes specific, and therefore, testable predictions as to the general features of planetary systems. An inescapable consequence of this paradigm is that planetary systems should be found in association with many, perhaps most, stars. At the time of this writing, however, there is as yet no confirmed observational evidence for the existence of another planetary system. This does not mean that the paradigm is faulty, nor does it imply an absence of progress. Indeed, the opposite is the case, and prospects for the future are;excellent. NASA is progressing with a program, starting with an aggressive ground-based effort, to be followed with an astrometric system in low-Earth orbit. Visions beyond that include observatories on the Moon. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.