Astronomers resolve visible blast wave from gamma-ray burst

Gamma-ray bursts (GRBs) are mysterious flashes of high-energy light that are detected about once a day somewhere in the sky. However, their origin remains unknown to astronomers, most of whom believe GRBs are enormous explosions that occur far across the Universe. Now for the first time, astronomers have resolved the visible blast wave produced by a gamma-ray burst. By taking advantage of a fortuitous cosmic alignment, a team of scientists was able to focus the light from a gamma-ray event halfway across the universe. The researchers were able to achieve this elusive goal: to see the ring-shaped structure caused by the gamma-ray burst because of "gravitational microlensing." Predicted by Einstein's theory of general relativity, microlensing occurs when the light from a very distant source -- in this case, a gamma-ray burst -- is amplified by the gravity of an intervening object.