CONFIRMATION OF EARTH-MASS PLANETS ORBITING THE MILLISECOND PULSAR PSR B1257+12

The discovery of two Earth-mass planets orbiting an old (similar to-10 (9) years), rapidly spinning neutron star, the 6.2-millisecond radio p ulsar PSR B1257+12, was announced in early 1992. It was soon pointed o ut that the approximately 3:2 ratio of the planets' orbital periods sh ould lead to accurately predictable and possibly measurable gravitatio nal perturbations of their orbits. The unambiguous detection of this e ffect, after 3 years of systematic timing observations of PSR B1257+12 with the 305-meter Arecibo radiotelescope, as well as the discovery o f another, moon-mass object in orbit around the pulsar, constitutes ir refutable evidence that the first planetary system around a star other than the sun has been identified.