FIFTH FORCE experiments are increasingly giving negative results. New measurements have demonstrated that a fifth force could be no more than about a trillionth as strong as gravity. (Science News, 22 September, p. 183) THE MAGELLAN SPACECRAFT map of Venus (2% of the surface so far) provides images 10 to 100 better than previous radar surveys. Strange tectonics--plentiful volcanoes and weird fracture systems--are at work. (NY Times, 26 September, p. A1) SUPERCONDUCTORS BEYOND 123: Robert Cava of AT&T Bell Labs reviews recent research on the thallium and bismuth superconductors and discusses prospects for higher critical temperatures. (Scientific American, August 1990) GRAVITATIONAL-WAVE ASTRONOMY may truly come into being in the next few years with the advent of new facilities such as the Caltech-MIT Laser Interferometer Gravitational Wave Observatory. So far only indirect evidence for gravitational waves can be inferred, in this case from the decaying mutual orbit of the two neutron stars in the pulsar system PSR 1913+16. (Mosaic Magazine, Summer 1990, published by the NSF) SOLAR CELLS may be better at converting sunlight into heat than into electricity, some researchers believe. The record efficiency for conversion to electricity, a tandem GaAs and Si cell at Sandia, is 31%. The theoretical limit is thought to be 40%. But thermal conversion may be more efficient and, besides, a great deal of the world's energy consumption goes toward the production of heating anyway. (New Scientist, 22 September, p. 48) METEOR COMPOSITION: unlike earth rocks which in the course of time have been melted and recrystallized into different forms, meteors have remained largely unchanged from when the solar system began and even before. Diamonds found in some meteors may have been produced by chemical vapor deposition, a process (also used in making diamonds artificially) that might occur in the outer layers of stars and supernovas. (New Scientist, 15 September, p. 46)