NULLED STARLIGHT. Under the right circumstances light from two separated telescopes can be combined to create a signal whose spatial resolution is better than that for either of the single telescopes. This interferometry technique can also be used in reverse: the light paths for the two beams can be adjusted to create not a maximum but a minimum. Thus the star's light can be nulled out. Astronomers have demonstrated this principle by canceling the image of the star Betelgeuse, leaving behind the faint glow of a surrounding dust nebula. The researchers expect that with adaptive optics, a ground-based nulling system could be used to image Jupiter-sized planets around nearby stars beyond the sun by subtracting the distracting stellar glare. (Hinz et al., Nature, 17 September 1998.)