Long gamma-ray burst and afterglow, illustration. Long gamma-ray bursts (GRBs) are high-energy explosions in the universe that last for two seconds or more. These brief flashes of high-energy light occur as a result of some of the universe's most explosive events, such as the birth of black holes. When a rapidly rotating star runs out of fuel in its core and collapses, a black hole forms at the centre of the star. Near the star, particle jets driven by matter falling towards the black hole erupt from the surface at nearly the speed of light, producing the GRB and its afterglow. To detect a GRB, one of these jets must point towards the Earth.