Number 145 (Story #2), September 28, 1993 by Phillip F. Schewe and Ben Stein MICROLENSING EVENTS HINT AT THE EXISTENCE OF DARK MATTER. Just as the presence of galaxies along the line of sight to a distant quasar will distort the image of the quasar via a gravitational lensing effect (making the quasar appear as two or more spots or as an arc), so the image of a nearby object such as a star might be distorted by the gravitational influence of unseen dark matter lying between us and the star. This hypothesis has been put to the test by two survey projects which scan millions of stars in the Large Magellanic Cloud, the nearby satellite galaxy. These stars are close enough to be seen clearly but far enough away so that a sufficient amount of dark matter---which may reside in the halo around the Milky Way---would be present to distort the stars' images. At a recent meeting in Italy, Charles Alcock of Livermore spoke on behalf of a US/Australian team. He announced one such "microlensing" event, in which a star's apparent brightness changed considerably over a short time, presumably by the interposing presence of dark matter in the form of massive compact halo objects, or MACHOs. Michel Spiro of Saclay in France also reported that his group had observed two microlensing candidate events. Some astronomers at the meeting believed that it was too early to attribute the star-image distortions to dark matter. (New York Times, 21 Sept. 1993)