Number 153 (Story #1), November 29, 1993 by Phillip F. Schewe and Ben Stein GRAVITATIONAL MICROLENSING OF QUASAR IMAGES , the distortion of quasar light by compact substellar objects lying along the line of sight between Earth and the quasars, may explain the long-term luminosity variations of many quasars. M.R.S. Hawkins of the Royal Observatory at Edinburgh, UK has analyzed 17 years' of data from a large-scale quasar monitoring program and reports that most of the 300 quasars in the sample have luminosities which vary semi-sinusoidally with a maximum-to-minimum timescale of about five years. The timescales do not seem to vary with redshift. Hawkins asserts that this variability pattern is inconsistent with any known mechanism intrinsic to quasars themselves and is much more likely to be associated with microlensing. (Nature, 18 Nov. 1993.) Only a few months ago, two teams of astronomers attributed the variability of several stars in the Large Magellanic Cloud to the microlensing influence of presumed massive compact halo objects (MACHOS) in our galaxy. (Update 145.)