Bright Lights, Big Mystery; August 1998; Scientific American Magazine; by Musser; 2 Page(s)

Hardly an astronomical announcement makes the front pages without being said to overturn all existing theories. Gammaray bursts are one of the few things for which this has actually been true. These seemingly random flashes--which, if you had gamma-ray vision and didn¿t blink at the wrong time, would outshine the rest of the sky--were long thought to originate in our galaxy. But that theory foundered in 1991, when the Compton Gamma Ray Observatory satellite detected bursts all over the sky, not only in the Milky Way. Another hypothesis, in which bursts occur just outside our galaxy, crumbled last year when the first distance measurement of a burst put it too far away. Although astronomers now agree that the bursts are some kind of megaexplosion in distant galaxies, they still appear on most top-10 lists of cosmic mysteries.

This past spring astronomers reported the distances to two new bursts-- which, at first glance, seemed to scuttle some of the few remaining plausible explanations. The first of these bursts, spotted last December 14 by the Beppo- SAX satellite, occurred in a galaxy 12 billion light-years away, according to observations by Shrinivas R. Kulkarni and S. George Djorgovski of the California Institute of Technology. To be so bright at such a distance, the burst must have shone more brilliantly than any object previously recorded.