interferometry - (n.)
an astronomical technique in which the images from two or more telescopes are superimposed. Interferometry has many uses, and one of the most intriguing is its ability to cancel out the light from a point source such as a star by superimposing the images in such a way that the oscillations in light intensity from one image are the reverse of the oscillations from the other image. With this method, planets orbiting the star can be directly observed, and the composition of their atmospheres can be investigated using spectral analyses. Note that this has not yet been accomplished as of summer 2000.