Illustration of the gamma-ray burst GRB 190114C. Gamma-ray bursts are the most powerful explosions in the Universe, emitting most of their energy in gamma rays (white jet). Hubble Space Telescope observations suggest that this particular burst was so powerful because the collapsing star was sitting in a very dense environment, right in the middle of a bright galaxy 5 billion light years away. Gamma rays are light which is much more energetic than the visible light we can see with our eyes.