GRAVITATIONAL FRAME-DRAGGING IS OBSERVED . Just as an electric charge emits an electric field and (if the charge is in motion) a magnetic field, so a massive body should, according to general relativity, emit a static gravitational field and (if the body is moving or rotating) an extra "gravitomagnetic" field (see Update 295 and the accompanying figure). Two groups of astronomers, one based in Rome (Luigi Stella, stella@coma.mporzio.astro.it) and one at MIT (Wei Cui, cui@space.mit.edu), now claim to have detected experimental evidence for this force in the form of subtle modulations in the x-ray signals coming from neutron stars and monitored by the Rossi X-Ray Timing Explorer (RXTE) satellite. The phenomenon is sometimes called "frame dragging" since its source is the distortions of space-time caused by the rotating mass. The results were reported yesterday at the High Energy Astrophysics Division meeting of the American Astronomical Society in Colorado.