Snapshots of Alien Worlds--The Future of Interferometry

The recent discovery of extrasolar planets illustrates the difficulties astronomers are faced with when trying to identify and characterize distant, faint objects. Optical and infrared interferometry have the potential for providing images of such objects, and may also show fine structure on distant stars, but are difficult to implement. Several international projects, ground-based and in space, are now underway for implementing such interferometers, and an even more ambitious concept - the hyper-telescope in which many segments, spaced kilometers apart but only meters in diameter, form a sparse giant mirror spanning hundreds or thousands of kilometers - is receiving increasing attention, bringing images of extrasolar planets and stars into the realm of possibility.