Number 102 (Story #3), November 10, 1992 by Phillip F. Schewe and Ben Stein SUPERMASSIVE BLACK HOLES probably exist, but astronomers won't be convinced merely by the impressive increase in luminosity of starlight toward the center of certain galaxies. According to Alan Dressler of the Carnegie Institution, conclusive evidence for black holes would come from the spectroscopic study of the movement of stars in the vicinity of the hole. The necessary high resolution may come with a rejuvenated Hubble Space Telescope or with the new optical telescopes being built atop Mauna Kea. Based on preliminary studies of star motion, the galaxies most likely to be harboring supermassive black holes are Andromeda, its satellite galaxy M32, and NGC3115 (whose candidate black hole would have a mass of more than a billion solar masses). In the long run, it may be easier to hunt for black holes in relatively placid galaxies like these, where the lack of the energy glare associated with active galaxies can only make easier the task of viewing star motion near the galactic core. As for our own presumed resident black hole, studies of the Milky Way's central precinct are hindered by viewing problem of another sort, namely the presence of dust. Nevertheless, indirect measurements of star motion are consistent with the idea of a black hole at the galactic core. (Science News, 31 Oct. 1992.)