Artist's impression of GRB 260310A. A massive star collapses and launches a jet made up of a narrow, ultrafast core (white beam) wrapped in a broader and slower outflow. The jet points away from Earth. Researchers first saw light from the jet's outer wings and only later from its energetic core. The inset shows the image acquired by the Large Binocular Telescope, displaying the bright optical afterglow (marked) next to its host galaxy. Credit: Fortuna / Yang / ERC BHianca

A gamma-ray burst (GRB) that has confounded astronomers is one of the brightest cosmic light shows in the past 20 years.…