virtual telescope, a computerized interferometer (see interference) that merges the images from two or more telescopes to obtain a single, large, enhanced image. The image in each telescope is made from electromagnetic waves (light waves from an optical telescope, radio waves from a radio telescope), each wave having peaks and valleys. Combining several waves into one makes the peaks higher and the valleys lower, resulting in a single, enhanced wave. This tends to make stars appear to be brighter and to increase the distances at which celestial objects can be studied. The peaks and valleys can also be made to cancel each other out (in a process called nulling interferometry) to permit the selective diminishment of the brightness of the light from a star so that, for example, a dimmer star or planet can be studied.